Hey, could you pls send me the chem & physics resources you were talking about?
My Email is: aum8888@gmail.com
Hey! I have a question...
In the production of Aluminum, Sodium Hydroxide is used to separate Aluminum Oxide from the impurities in bauxite ore. The Main impurity in the ore is Iron(3) Oxide. Aluminum Oxide is an amphoteric oxide whilst Iron(3) Oxide us a basic oxide.
Suggest how these two oxides can be separated by the addition of aqueous Sodium Hydroxide.
i hav a question...if the question has an acid and a base given and they mention tht water IS the acid and they ask Y does water behaves like acid....wat is the answer and plz briefly explain
do u want me to send it?
the reductant is zinc and the oxidant is hydrogen
first of all the definitions of reductant and oxidant are
reductant - causes the other element to be reduced. when this happens the reductant is oxidised (loses electrons)
oxidant - cause the other element to be oxidised. when this happens the oxidant is reduced (gains electrons)
zinc is the reductant because it is being oxidised. the metal is being transformed into ions and electrons are given out (hence the zinc rod becomes thinner)
hydrogen is the oxidant because the hydrogen ions in the electrolyte is being changed into hydrogen gas(hydrogen is being reduced)
I need help in chemistry oct/nov 08 second varient paperi actually got this question for my mocks
Q 7ai)
Thankyou but wont we use the formulaa???I need help in chemistry oct/nov 08 second varient paperi actually got this question for my mocks
Q 7ai)
here's the working
volume of oxygen left
according to question according to equation
1 mol 6.5 mol
if 20cm3 x??
so 20 x 6.5 = 130cm3
150-130 = 20cm3
so volume of oxygen left = 20cm3
volume of carbondioxide formed
1 4
20 x??
so 20 x 4 = 80
volume of carbondioxide formed = 80cm3
Thankyou but wont we use the formulaa???I need help in chemistry oct/nov 08 second varient paperi actually got this question for my mocks
Q 7ai)
here's the working
volume of oxygen left
according to question according to equation
1 mol 6.5 mol
if 20cm3 x??
so 20 x 6.5 = 130cm3
150-130 = 20cm3
so volume of oxygen left = 20cm3
volume of carbondioxide formed
1 4
20 x??
so 20 x 4 = 80
volume of carbondioxide formed = 80cm3
n umm why did u subtracted it form 150?
alright thankyouThankyou but wont we use the formulaa???I need help in chemistry oct/nov 08 second varient paperi actually got this question for my mocks
Q 7ai)
here's the working
volume of oxygen left
according to question according to equation
1 mol 6.5 mol
if 20cm3 x??
so 20 x 6.5 = 130cm3
150-130 = 20cm3
so volume of oxygen left = 20cm3
volume of carbondioxide formed
1 4
20 x??
so 20 x 4 = 80
volume of carbondioxide formed = 80cm3
n umm why did u subtracted it form 150?
no there is no need to use a formulae
n oxygen is in excess n we want to find the volume of oxygen left at the end of experiment
so 150-130= 20
wat are macromolecular structures and giant molecular stictures?i keep on 4getting these 2 all the tym...:(MAcro molecules:they are giant covelant sturcures which have million of atoms held together by covelent bond
I believe both are the same-giant and macroits not a question...i just need da meanings... ;D
can u give me the exact question. w8 hybye said was right in a way. if your talking about giant covalent molecules then it's diamond, silica,graphite
germanium is an element so that is wrong
ahan true!! but i meant that which one is more improtant to study first for revision.
Thankyou but wont we use the formulaa???I need help in chemistry oct/nov 08 second varient paperi actually got this question for my mocks
Q 7ai)
here's the working
volume of oxygen left
according to question according to equation
1 mol 6.5 mol
if 20cm3 x??
so 20 x 6.5 = 130cm3
150-130 = 20cm3
so volume of oxygen left = 20cm3
volume of carbondioxide formed
1 4
20 x??
so 20 x 4 = 80
volume of carbondioxide formed = 80cm3
n umm why did u subtracted it form 150?
no there is no need to use a formulae
n oxygen is in excess n we want to find the volume of oxygen left at the end of experiment
so 150-130= 20
u will b knowing the total oxidation state of the compound ...thank u so much 4 ur response. (+rep) i read the same method in one of the other sites and i understand very well now.
if its a compound .. then the oxidation state is zero
if its an ion then the oxidation state is the final charge on that ion
now suppose we take KMnO4 .. the final oxidation sate is zero .. because there is no overall charge on the compound
suppose u wanna get the oxidation number of Mn .. assume it to be x
we know that K is +1 , and O is -2 .... this is how u do it
(+1) + x + (-2)(4) = 0
solve algebrically so x = 7
hey could anyone gimme the list of water soluble and insoluble gases
ahan true!! but i meant that which one is more improtant to study first for revision.
ok i guess:
1)Organic chemistry
2)Metals
3)Electrolysis
4)Rust prevention
5)Sulphur, Air, Water, Carbohydrates
I think.... all will come...but Metals is an important topic...
guys there is a rumour, saying that there will be no
- Organinc chemistry,
- Reactivity Series
- moles
-Endo or Exo thermic thingys
however will be
Rates of Reactions,
Bonding
and da rest
ur welcome
i am soo bloody confident
Hey, does anyone know what colour change occurs when potassium iodide is reduced??? Its in the syllabus, you gotta know this!!!!
I was thinking the same too but i thought i was wronge .. (+rep) Thanx for the helplol its ok which yr was this question in?
Hey, does anyone know what colour change occurs when potassium iodide is reduced??? Its in the syllabus, you gotta know this!!!!
Colour changes from colourless to dark brown and a black solid may form as well ;)hope i helped
Hey, does anyone know what colour change occurs when potassium iodide is reduced??? Its in the syllabus, you gotta know this!!!!
Colour changes from colourless to dark brown and a black solid may form as well ;)hope i helped
+REP u for the 2nd time as i promised!!
An alloy contains zinc and Copper . A small sample of this alloy was dissolved in acid to give a soluion containing zinc and copper ions.
Explain what would happen when an excess of each of the following reagents is separatly added to this solution.
i) Iron Fillings
effervescenses-bubbles of colourless gas. With lighted splint it pops (Hydrogen)
------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------ [2]
ii) Sodium Hydroxide
------------------------------------------------------------------------------------------
zinc-white precipetation soluble in excess
------------------------------------------------------------------------------------------ [2]
Copper-blue ppt becomes soluble in excess solution changes to deep blue(royal)
I'm not sure of the answer!!
Hey, does anyone know what colour change occurs when potassium iodide is reduced??? Its in the syllabus, you gotta know this!!!!umm there is no color for iodine ion i am sure
hey lana
it goes like this
3 mols of co2 give 15 cm3
so what will 5 mols of oxygen give?
its simply cross multiplication
no. of mols volume
3 15
5 ?
so (5 x 15)
---------= 25cm3
3
then to get the volume for propanol (C3H8) which is 1 mol ,do the same
no. of mols volume
3 15
1 ?
so (1 x 15)
---------- = 5cm3
3
so the answer is for oxygen=25 and for propanol=5
hope u understand, any confusion or difficluties or help, plz do ask me
yes its absolutely like thisiron production
by the way how is the production of iron in the blast furnace
if propanol and propanoic acid react they give an ester can anybody please name that ester and draw it's structural formula...
thanks
Can someone explain me Q5 (p3 M/J 08)
its equlibirum i
i need to understand
I POSTION OF EQULIBRUM n WHAT HAPPENEDS ??? ???
tha really helped me thankyou soo much + rep for u By the way i have one question so during a rection the conditions should be EXOTERMIC OR ENDOTERMIC??Can someone explain me Q5 (p3 M/J 08)
its equlibirum i
i need to understand
I POSTION OF EQULIBRUM n WHAT HAPPENEDS ??? ???
Q5ai) The concentration of the reactants will increase (as the equilibrium shifts to the left) and the concentration of the products will decrease.
*Equilibrium justmeansthe 'balance' of a reaction; when it says the equilibrium shifts left, it refers to the fact that the reaction goes backwards and instead of producing more products, the reactants are produced.
5aii)-The position shifts to the left because decreasing the pressure on the reaction favours the side of the equation with the highest volume of gases (a.k.a. moles/molecules of gas).
5b)-The forward reaction is exothermic, because a decrease in temperature favours the forward reaction, so it must be exothermic.
Our teacher told us to think of the equlibrium like this: there is a naugty boy and he does exactly the opposite of what you tell him to do. So, using the above scenario, lowering the pressure favours the side with higher volume of gas. And, lowering the temperature favours the exothermic temperature (heat given out). If you see, in both the cases the opposite is happening.
I hope its clear :)
tha really helped me thankyou soo much + rep for u By the way i have one question so during a rection the conditions should be EXOTERMIC OR ENDOTERMIC??Can someone explain me Q5 (p3 M/J 08)
its equlibirum i
i need to understand
I POSTION OF EQULIBRUM n WHAT HAPPENEDS ??? ???
Q5ai) The concentration of the reactants will increase (as the equilibrium shifts to the left) and the concentration of the products will decrease.
*Equilibrium justmeansthe 'balance' of a reaction; when it says the equilibrium shifts left, it refers to the fact that the reaction goes backwards and instead of producing more products, the reactants are produced.
5aii)-The position shifts to the left because decreasing the pressure on the reaction favours the side of the equation with the highest volume of gases (a.k.a. moles/molecules of gas).
5b)-The forward reaction is exothermic, because a decrease in temperature favours the forward reaction, so it must be exothermic.
Our teacher told us to think of the equlibrium like this: there is a naugty boy and he does exactly the opposite of what you tell him to do. So, using the above scenario, lowering the pressure favours the side with higher volume of gas. And, lowering the temperature favours the exothermic temperature (heat given out). If you see, in both the cases the opposite is happening.
I hope its clear :)
Oh, and in the case of the question fro M/J 08, it is where you have to combine the equilibrium knowledge with the exo/endo knowledge. You know that in equilibrium Qs, the opposite happens. So, if you COOL the reaction, it will try to HEAT up and increase its temp, which is by giving out heat energy (EXOTHERMIC)tha really helped me thankyou soo much + rep for u By the way i have one question so during a rection the conditions should be EXOTERMIC OR ENDOTERMIC??Can someone explain me Q5 (p3 M/J 08)
its equlibirum i
i need to understand
I POSTION OF EQULIBRUM n WHAT HAPPENEDS ??? ???
Q5ai) The concentration of the reactants will increase (as the equilibrium shifts to the left) and the concentration of the products will decrease.
*Equilibrium justmeansthe 'balance' of a reaction; when it says the equilibrium shifts left, it refers to the fact that the reaction goes backwards and instead of producing more products, the reactants are produced.
5aii)-The position shifts to the left because decreasing the pressure on the reaction favours the side of the equation with the highest volume of gases (a.k.a. moles/molecules of gas).
5b)-The forward reaction is exothermic, because a decrease in temperature favours the forward reaction, so it must be exothermic.
Our teacher told us to think of the equlibrium like this: there is a naugty boy and he does exactly the opposite of what you tell him to do. So, using the above scenario, lowering the pressure favours the side with higher volume of gas. And, lowering the temperature favours the exothermic temperature (heat given out). If you see, in both the cases the opposite is happening.
I hope its clear :)
Endothermic is when energy is taken in, which happens when bonds are broken. Exothermic is heat given out, and this happens when new bonds are formed. In a reaction, endothermic and exothermic happens simultaneously. What determines the overall type of the reaction is this: if they tell you in a question that the energy change is -115 celsius, for example, the minus sign would indicate that the heat energy given out is more than heat energy taken in. So, the overall reaction is exothemic. Consequently, if its a positive sign, tht would indicate that heat energy taken in is more than heat energy given out, indicating that the reaction is endothermic. Also, sometimes, in question they ask you to explain why the reaction is exothermic or endotermic. In that case, you would answer using the idea of bond forming and bond breaking and the relative energy changes involved (as I have explained above).
I hope this helped. :)
THanx alot + rep 4 u:)Oh, and in the case of the question fro M/J 08, it is where you have to combine the equilibrium knowledge with the exo/endo knowledge. You know that in equilibrium Qs, the opposite happens. So, if you COOL the reaction, it will try to HEAT up and increase its temp, which is by giving out heat energy (EXOTHERMIC)tha really helped me thankyou soo much + rep for u By the way i have one question so during a rection the conditions should be EXOTERMIC OR ENDOTERMIC??Can someone explain me Q5 (p3 M/J 08)
its equlibirum i
i need to understand
I POSTION OF EQULIBRUM n WHAT HAPPENEDS ??? ???
Q5ai) The concentration of the reactants will increase (as the equilibrium shifts to the left) and the concentration of the products will decrease.
*Equilibrium justmeansthe 'balance' of a reaction; when it says the equilibrium shifts left, it refers to the fact that the reaction goes backwards and instead of producing more products, the reactants are produced.
5aii)-The position shifts to the left because decreasing the pressure on the reaction favours the side of the equation with the highest volume of gases (a.k.a. moles/molecules of gas).
5b)-The forward reaction is exothermic, because a decrease in temperature favours the forward reaction, so it must be exothermic.
Our teacher told us to think of the equlibrium like this: there is a naugty boy and he does exactly the opposite of what you tell him to do. So, using the above scenario, lowering the pressure favours the side with higher volume of gas. And, lowering the temperature favours the exothermic temperature (heat given out). If you see, in both the cases the opposite is happening.
I hope its clear :)
Endothermic is when energy is taken in, which happens when bonds are broken. Exothermic is heat given out, and this happens when new bonds are formed. In a reaction, endothermic and exothermic happens simultaneously. What determines the overall type of the reaction is this: if they tell you in a question that the energy change is -115 celsius, for example, the minus sign would indicate that the heat energy given out is more than heat energy taken in. So, the overall reaction is exothemic. Consequently, if its a positive sign, tht would indicate that heat energy taken in is more than heat energy given out, indicating that the reaction is endothermic. Also, sometimes, in question they ask you to explain why the reaction is exothermic or endotermic. In that case, you would answer using the idea of bond forming and bond breaking and the relative energy changes involved (as I have explained above).
I hope this helped. :)
You are most welcome :)ookay but i used tog et confused bcuz its kinetic thoer incres temp reaction increses but in qs like these its like more EQULIBRIUM my teacher is like its not that hard how much ure making it
hi. I was wondering does anyone have any good notes on salt preparation? Or can you please explain it to me? (all the methods and such) Also..this is going to sound really stupid but can anyone be bothered to put together a list of compounds and their colours (the one's required?) I have a couple of them but I'm not sure if they're a)needed and b) correct.
Thank you. Oh and if it helps I'll post the list of the colours I DO know so you can just tell me the one's I'm missing out or the ones which I've got wrong.
Here it is:
1. CuCO3 ===>Green
2. CuO ===> Black
3. CuSO4 ===>White
4. CuSO4.5H2O ===> Blue
5. CoCl2.6H2O ===> Pink
6. CoCl2 ===> Blue
7. MnO2 ===> Shiny Black
8. KMnO4 ===> Purple
9. K2Cr2O7 ===> Orange
10. CuCl2 ===> Blue
Again, Thank you help will be much appreciated. ^^
THANKS!! And how do we know if a reaction is a redox reaction!? ;D
here is a question, since no one has any to ask, lol
What is the role if chlorophyll in green plants? [3]
here is a question, since no one has any to ask, lol
What is the role if chlorophyll in green plants? [3]
I think, acts as a catalyst, or its the place where reactions(photosynthesis) takes place. I'm not sure. :D
It has the suitable condetions for the reactions to take place? :-\here is a question, since no one has any to ask, lol
What is the role if chlorophyll in green plants? [3]
I think, acts as a catalyst, or its the place where reactions(photosynthesis) takes place. I'm not sure. :D
close, but not fully right
It has the suitable condetions for the reactions to take place? :-\here is a question, since no one has any to ask, lol
What is the role if chlorophyll in green plants? [3]
I think, acts as a catalyst, or its the place where reactions(photosynthesis) takes place. I'm not sure. :D
close, but not fully right
so I got one mark right! :P anyways thanks :DIt has the suitable condetions for the reactions to take place? :-\here is a question, since no one has any to ask, lol
What is the role if chlorophyll in green plants? [3]
I think, acts as a catalyst, or its the place where reactions(photosynthesis) takes place. I'm not sure. :D
close, but not fully right
no not really, its for 3 marks so u must have 3 point,
Ans: absorbs light energy from the sun[1], and acts as a catalyst[1] in the reaction between carbon dioxide and water[3]
and if u want give the symbolic reaction (its better to give it)
so I got one mark right! :P anyways thanks :DIt has the suitable condetions for the reactions to take place? :-\here is a question, since no one has any to ask, lol
What is the role if chlorophyll in green plants? [3]
I think, acts as a catalyst, or its the place where reactions(photosynthesis) takes place. I'm not sure. :D
close, but not fully right
no not really, its for 3 marks so u must have 3 point,
Ans: absorbs light energy from the sun[1], and acts as a catalyst[1] in the reaction between carbon dioxide and water[3]
and if u want give the symbolic reaction (its better to give it)
Biology FTW! :P
Biology FTW! :P
yeah....yeah :P
CHLOROPHYLL......... GREEN PLANTS.......chem???? which paper dude........chem... :P
Biology FTW! :P
yeah....yeah :P
CHLOROPHYLL......... GREEN PLANTS.......chem???? which paper dude........chem... :P
actully, june 2002 Q2)b is about the photosynthesis formula. It doesn't have anything to do with chlorophyll :-\Biology FTW! :P
yeah....yeah :P
CHLOROPHYLL......... GREEN PLANTS.......chem???? which paper dude........chem... :P
it came in paper 3 november 99, Q2// and june 2002 Q2)b
actully, june 2002 Q2)b is about the photosynthesis formula. It doesn't have anything to do with chlorophyll :-\Biology FTW! :P
yeah....yeah :P
CHLOROPHYLL......... GREEN PLANTS.......chem???? which paper dude........chem... :P
it came in paper 3 november 99, Q2// and june 2002 Q2)b
actully, june 2002 Q2)b is about the photosynthesis formula. It doesn't have anything to do with chlorophyll :-\Biology FTW! :P
yeah....yeah :P
CHLOROPHYLL......... GREEN PLANTS.......chem???? which paper dude........chem... :P
it came in paper 3 november 99, Q2// and june 2002 Q2)b
well photosynthesis, is all about chlorophyll, isnt it, and also think about it they wouldnt give u four marks just for writing the formula
well Bessy i think that potassium is yellow not iodine...
and ioden is purple/black that wat i think...
and +rep if i m correct :)
Reactivity table /\
|
Potassium | [PETER'S]
Sodium | [SISTER]
Calcium | [CAN]
Magmesium | [MURDER]
aluminium | [A]
carbon | [CONSTIPATED]
zinc | [ZEBRA]
iron | [IN]
tin | [THE] / Increasing of reactivity
lead | [liGHT]
hydrogen | [HOUSE]
copper | [CAN]
silver | [SHE]
gold | [GO]
platinum | [PLEASE?]
Sorry could not draw a good arrow for the increasing of reactivity...hope this helps
Reactivity table /\
|
Potassium | [PETER'S]
Sodium | [SISTER]
Calcium | [CAN]
Magmesium | [MURDER]
aluminium | [A]
carbon | [CONSTIPATED]
zinc | [ZEBRA]
iron | [IN]
tin | [THE] / Increasing of reactivity
lead | [liGHT]
hydrogen | [HOUSE]
copper | [CAN]
silver | [SHE]
gold | [GO]
platinum | [PLEASE?]
Sorry could not draw a good arrow for the increasing of reactivity...hope this helps
my friend tought me an easier way to study these...luk up^^^^
HOPES THIS HELPS :D
yes..correct...forgot lithium
anyway we can change it a bit
peter's sister lauren can murder a ..............
lol
haha
I have a couple of doubts people:
a) Could somebody help me out with naming the 'isomers' for example, how should we know where to write 1,2-dimethyl, etc etc
b) Displacement of ammonia from its salts (explain please!)
c) Displacement reactions in metals, e/g with nitrates, hydroxides etc!!
May/Jun 2008 //Q6)c)(ii)Thats easy, respiration is the release of energy using oxygen & glucose to give CO2 + water + energy
another Question since no one is askin anything
Pasteur said that fermentation was respiration in the absence of air. Suggest a
definition of respiration.[2]
Can someone give me a brief explanation on the Extraction of Aluminium?
I always get confused
Ah Thanks man, always got confused with the cryoliteCan someone give me a brief explanation on the Extraction of Aluminium?
I always get confused
aluminium is extracted by electrolysis, it is extracted from its orebauxite (Al2O3). and since pure aluminiumoxide melts at 2000 degree C, they add molten cryolite, which lowers the melting point to about 950, thus reducing costs, aluminium is produced at the cathode (Al3+ + 3e- goes to Al) and at the cathode (2O2- - 4e- goes to O2) a, also carbon dioxide may be produced when it reacts with the carbon electrode
u may get 1 markAh aite! its 2 marks right
cuz u have to say the release of energy by living cells from food
and By the way LIL WAYNE IS THE BEST RAPPER ALIVE , so stop hating
another question ..Wah do you mean? obtaining hydrogen from.....
Name 2 ways of obtaining hydrogen (on a large scale)?
another question ..Wah do you mean? obtaining hydrogen from.....
Name 2 ways of obtaining hydrogen (on a large scale)?
Oh then, i dont know that answer then =Panother question ..Wah do you mean? obtaining hydrogen from.....
Name 2 ways of obtaining hydrogen (on a large scale)?
i mean how would u obtain a large quaantity of hydrogen ?
and who the hell told u he has a ghost writer (pure bullshit)
another question ..Wah do you mean? obtaining hydrogen from.....
Name 2 ways of obtaining hydrogen (on a large scale)?
i mean how would u obtain a large quaantity of hydrogen ?
and who the hell told u he has a ghost writer (pure bullshit)
Which is more reactive Gold(Au) or Platinum(Pt)?
Which is more reactive Gold(Au) or Platinum(Pt)?
Which is more reactive Gold(Au) or Platinum(Pt)?
THANKS!! And how do we know if a reaction is a redox reaction!? ;D
shogun;s way might be alittle bit confusing, an easier way to memorize it:
Oxidation: gain of oxygen, loss of electrons, loss of hydrogen
Reduction: loss of ogygen, gain of electrons, gain of hydrogen
Examples: analyze shogun;s examples, cuz they are good examples, lol
What are the 3 conditions for the haber process?
What are the 3 conditions for the haber process?
heat pressure and temperature.
and also
name 2 ways of obtaining a large quantity of hydrogen
Oh really aite:
and Mastermind, this is all i need to tell u
1)im the one who has to die, when its time for me to die, so let me live my life the way i want to!!
2)if u leave ur leavin the best, so u will have to settle for less
3)look at the ice, ridicolous price, ur camera has never seen a picture this nice
4)swallow my words taste my thoughts and if its to nasty spit it back at me
5)u could love me or hate me , i swear it wont make me or break me
6)i know this world is so cold and decieving, but i keep my head up like my nose is bleedin
hahaha
and lastley take them shoes off ur teeth and stop runnin ur mouth
OHHH thats how! Thanks man, ill jus write eat bean =Pand also
name 2 ways of obtaining a large quantity of hydrogen
electrolyse water, break up hydrocarbons
OR EAT BEANS
and also
name 2 ways of obtaining a large quantity of hydrogen
electrolyse water, break up hydrocarbons
OR EAT BEANS
Hydrogen Ion is obtained by removing one electron from hydrogen atom.
& the best rapper alive is Em, without a doubt
Whats the difference between a Protein & a Synthetic Polymer?
& lil wayne everyone’s got a favorite rapper. Even ur favorite rapper has a favorite rapper.
okie, i know this is a stupid question but wot is brine again?
whats the difference between condensation polymerisation nd addition polymerisation ???
whats the difference between condensation polymerisation nd addition polymerisation ???condensation polymerisation needs 2 polymers, and here simple substances like water is eliminated, its not for double bonds carbon (like ethene).
hi. I was wondering does anyone have any good notes on salt preparation? Or can you please explain it to me? (all the methods and such) Also..this is going to sound really stupid but can anyone be bothered to put together a list of compounds and their colours (the one's required?) I have a couple of them but I'm not sure if they're a)needed and b) correct.
Thank you. Oh and if it helps I'll post the list of the colours I DO know so you can just tell me the one's I'm missing out or the ones which I've got wrong.
Here it is:
1. CuCO3 ===>Green
2. CuO ===> Black
3. CuSO4 ===>White
4. CuSO4.5H2O ===> Blue
5. CoCl2.6H2O ===> Pink
6. CoCl2 ===> Blue
7. MnO2 ===> Shiny Black
8. KMnO4 ===> Purple
9. K2Cr2O7 ===> Orange
10. CuCl2 ===> Blue
Again, Thank you help will be much appreciated. ^^
hi, there are 4 ways of making salts ill explain to u all of them
a) to make inoluble salts(barium sulphate):
1) take 2 soluble forms of the chemical used to make barium sulphate, eg:barium nitrate and sulphuric acid
2) add barium nitrate to sulphuric acid then filter the mixture
3)u will get the residue(the insoluble part,i.e barium sulphate) and the filterate (of whats left of the liquid part)
4) wash those crystals of barium sulphate with distilled water and dry them using 2 filter papers(this avoides the braking of crystals) and finally u got clear barium sulphate.
b) to make salts from very reactive metals (eg, sodium, pottasium or any of the first 3 metals in the reactivity series)
1)lets say we want to make sodium chloride(NaCl, or table salt).such process where making salts with reactive metals are done with and experiment called TITRATION.alright now u will need burette and pippete.its usually done with appropriate alkali (eg for this one sodium hydroxide(NaOH)) with an apropriate acid(eg for this one hydrochloric acid (HCl)) this is called NEUTRALISATION where alkalis react with acid to from salt and water.
2) FROM THE PIPPETE pour some unkown amount of sodium hydroxide to a conical flask
3)add an indicator pheonolphthalein which turns pink in colur when in alkali.
4)using burette pour out the acid hydochloric acid, keep doin tht untill tht pink colour dissapers.
5)then pour out every thing from the conical flask, repeat the experiment with the same amount of the alkaline and with out using the indicator, this is done because the indicator present makes the salt impure.
6)bring the above colourless solution in a china dish and evaporate it untill crystalls apear
then filter the crystals out and washed them with distilled water and dry them between 2 filter papers.
and u finally get pure sodium chloride.
c)to make salts from weak metals(magnesium to tin in the reactivity series)
1)lets say u want to make magnisium nitrate. do u remeber thos question i paper 6 where they say add in excess? this is the process of making salts with weak metals by adding things in excess.Alright now what we need is magnesium and an acid nitric acid.
2)take in a beaker nitric acid and add magnesium in excess to it, u will see effervecense appear due to liberation of oxygen. wait until the effervescence end. u will see excess pices of magnesium carbonate.
3)filter the mixture,to get the SOLUTION of magnesium ntrate , which is the filterate
4)take the filterate to a china dish, and evaporate to crystallisation point and then cool slowly till crystals are formed.
5)collect crystals again by filteration.wash it and dry it with filter papers.
d)to make salts from very week metals(eg copper nitrate)
1)alright this would be same as the above procedueres. take an acid like nitric acid, and take some amount of coper oxide.
2) pour some amount of nitric acid to the beaker and add excess copper oxide and warm it
3)now there wont be any effervecence here cuz the product of this reaction would be copper nitrate and water and no gas so no effervescence
4)filter the mixture, take the crystals and wash it and dry it as usually.
thts all for making salt.now the colours are alright, but rmember tht all oxides of group 1 and 2 metals are white in colour and oxides of transition are colourfull i think, but mostly its black.
ell any consufion or difficluties, or help u need plz do ask.
and plz + rep me, if everythings allright with my explanaition.hope u understand.
Heat until crystallisation point. Cool 'til crystals appear, then dry. ;D
Can anyone tell me what is modern proccess?
nov.2005 Q7)Heat until crystallisation point. Cool 'til crystals appear, then dry. ;D
Can anyone tell me what is modern proccess?
modern process for wat?
Heat until crystallisation point. Cool 'til crystals appear, then dry. ;Dhey.....ur 4gettin sum points...hv a luk on my post...
Can anyone tell me what is modern proccess?
Heat until crystallisation point. Cool 'til crystals appear, then dry. ;Dhey.....ur 4gettin sum points...hv a luk on my post...
Can anyone tell me what is modern proccess?
filterin n washin with distilled water are vry essential points.....
n wats modern process??
nov.2005 Q7)Heat until crystallisation point. Cool 'til crystals appear, then dry. ;D
Can anyone tell me what is modern proccess?
modern process for wat?
N2 + 3H2 <--> 2NH3 this is the habor process?
modern process is used to obtain what?
Thanks ;D
because at low pressure it will change to gas. So we keep it under high pressure so it stays as liquid and have a volume
Ok here's a question, list the uses of ployesters.synthestic or natural?
Polyesters(such as terylene) are used mostly for clothing, they don't usually ask you for more than one use.
I also have another question: one one of the past papers (may/june 04, question 4) I was doing, there was a graph showing volume of aq.sodium hydroxide plotted against height of precipitate of iron (III) chloride. There is a upwards sloping line which flattens at 6 mm on the y-axis.
The question then asks you to sketch the graph that would be obtained if iron (III) chloride had been used. The mark scheme says it would be the same, except it would have a max of 8 mm, not 6
I don't really understand how you get that answer...why is the ppt.of iron (III) chloride taller than iron (II) chloride? i didn't even know there was a difference besides the color?
thanks if anyone can help!
What are the physical and chemical properties of transition metals?
What about conducting electricity?
Oh ok, so the graph is exactly the same, except it flattens at 8 cm3?yeah it flattens at 8 cm3, and ur welcome
Thanks a lot, none of my friends could answer that question!
I meant in molten state, or in liquid stateWhat about conducting electricity?
yeah they do conduct electricity cuz they are METALS
I meant in molten state, or in liquid stateWhat about conducting electricity?
yeah they do conduct electricity cuz they are METALS
No.
My friend told me when it is molten it will have free electrons, which makes it conduct electricity...and as well as, when it's (aq). Is this true?
and for the "fractional distillation of crude oil"I don't think so. But you have to know their uses
do we need to noe da boiling range, chain length and percentage of each fraction?
for the fractions u dont have to know thier percentage or stuff, u just have to know which comes first, and what are they used for, and which fraction is which...Can you list them in order, with their uses!? ;D
and for the "fractional distillation of crude oil"I don't think so. But you have to know their uses
do we need to noe da boiling range, chain length and percentage of each fraction?
Yes. Your welcome :Dand for the "fractional distillation of crude oil"I don't think so. But you have to know their uses
do we need to noe da boiling range, chain length and percentage of each fraction?
sure? so only uses and the order rite?
thanks!
for the fractions u dont have to know thier percentage or stuff, u just have to know which comes first, and what are they used for, and which fraction is which...Can you list them in order, with their uses!? ;D
hey u guys
wat do we need to noe abt "soaps" in organic chem. i dont understand that part
thannkss
hey u guys
wat do we need to noe abt "soaps" in organic chem. i dont understand that part
thannkss
can sum1 pls clear my doubt on this?
can some one post about contact process and how sulphuric acid is made ?
and in moles stuff can some one post the formula;s required , and if you have any tips or easy way to work out the answers ? and solve
1- M/j 2005 paper 3 Q5 d)
2- O/N 2005 Q6 ( all parts )
thanks ALOT, you guys are Awesome specially shogun and lilWayne ( just dnt ovr react if ppl had diff. opinion about your fav rapper ;) )
thanks again
hey u guys
wat do we need to noe abt "soaps" in organic chem. i dont understand that part
thannkss
can sum1 pls clear my doubt on this?
all u need to know about soap is how to make one. which is by reacting fat (oil) with an alkali (like sodium hydoroxide) , the chemical name for soap is sodium sterate.
and about kerosene (the correct spelling,lol) is used as fuel for jet plane with it comes paraffin where both are in the 4rth fraction.
can some one post about contact process and how sulphuric acid is made ?
and in moles stuff can some one post the formula;s required , and if you have any tips or easy way to work out the answers ? and solve
1- M/j 2005 paper 3 Q5 d)
2- O/N 2005 Q6 ( all parts )
thanks ALOT, you guys are Awesome specially shogun and lilWayne ( just dnt ovr react if ppl had diff. opinion about your fav rapper ;) )
thanks again
oh shogun there is Q5 section d in Q4 there is no section d
lilwayne thanks but i could have looked up the answers in MS too :-X .. i wanna know how to do it like an explanation would be more good
i apologize if you find it insulting . im sorry
but the Question says " an excess of nickle carbonate 12g was added to 40cm3 of sulphuric acid , 2 mol/dm3"
what do they mean by 2 mol/dm3
ahhaa ,, so because they want more i only have to see how much moles they have right ?
we can see that H2SO4 is one mole and its mole is 0.08
so if NiCO3 is also one more then it will also be 0.08
right ?
tell me if i pass this part
yup, srry its the concentration od sulphuric acid,lol
lil wayne hos do i do get the maximum moles of hydrated salt....
yup, srry its the concentration od sulphuric acid,lol
lil wayne hos do i do get the maximum moles of hydrated salt....
its 0.08 cuz (1:1) ratio
eyy yall
err i was wonderin if sum1 cud upload tha marking schemes for the year 2000 may/ june n Oct/ nov
n also 2001!!
ayt
also was wonderin how many past papers shall i solve in order to get an A*? 8)
thanks guys i get the first part all now .. but about part ii the max moles , is it like always if there is one mole it will me 0.08 ?
and why we didnt use the 10.4 in anything ??
can some one just complete that part till the percentage yield thanks <3
somebody please explain this to me ...when a reaction cool or lose heat it's endothermic right ? because energy is taken in ? please correct me if I'm wrong because in pp3 in June 08 mark scheme it's the opposite !!! so I'm totally confused :-\
thanks alot
ooh ok !!! :P thanks allot and seriously lilwayne your the best !!! ;D
+rep for you
somebody please explain this to me ...when a reaction cool or lose heat it's endothermic right ? because energy is taken in ? please correct me if I'm wrong because in pp3 in June 08 mark scheme it's the opposite !!! so I'm totally confused Undecidedaa
Quotesomebody please explain this to me ...when a reaction cool or lose heat it's endothermic right ? because energy is taken in ? please correct me if I'm wrong because in pp3 in June 08 mark scheme it's the opposite !!! so I'm totally confused Undecidedaa
i think you are wrong .. because when a reaction lose heat means its exothermic and when it takes heat in then its endothermic when it loses energy then how is the energy takin in ? that happens in endothermic reactions where it takes energy in , exothermic gives energy out .
and MS is correct
no I'm right exothermic is when energy is given out so the temperature increases and endothermic is when energy is taken so the temperature decreases but i just misunderstood the question that's all ....!!!
Hey I got a question: how are organic/carboxylic acids made? Is it by acidifying, or is it by oxidizing with potassium magnanate(or another oxidizing agent, or both together? Just confused as to if both the methods are correct, and if they are supposed to be used together...
yes lilwayne though i have feelings that it will be
yes..correct...forgot lithiumHAHAHAHA!!!!!!!LOL!!!tht is so funny!!!
anyway we can change it a bit
peter's sister lauren can murder a ..............
lol
haha
lol lil wayne, wat u wanna be when u grow up?
how do we know if a reaction is endothermic?!
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???
how do we know if a reaction is endothermic?!
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???
it makes the sulphuric acid more dilute, so the bulb's brightness decreases. i think
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???
it makes the sulphuric acid more dilute, so the bulb's brightness decreases. i think
ur right, by the looks of it u will pass chem very well :P
is carboxylic acid and ethanoic acid the same?
so they r the same!is carboxylic acid and ethanoic acid the same?
ethanoic acid is used as a preservative and flavouring.
carboxylic acids are made by the oxidation of alcohols
is carboxylic acid and ethanoic acid the same?
thanxis carboxylic acid and ethanoic acid the same?
ethanoic acid is an example of carboxylic acid.
how do we know if a reaction is endothermic?!
The temp would fall, this is because it takes more energy/heat to break the bonds between the atoms, if it was exothermic, then more energy would be used to form new bonds, and the temp. raises
the heat source always has a higher temperature than the surroundinghow do we know if a reaction is endothermic?!
The temp would fall, this is because it takes more energy/heat to break the bonds between the atoms, if it was exothermic, then more energy would be used to form new bonds, and the temp. raises
correct me if im wrong but i thought it was the other way round
cuz endo takes in heat so temp rises(positive)
and exo gives out heat go temp falls(negative)
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???
it makes the sulphuric acid more dilute, so the bulb's brightness decreases. i think
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???
How can u test if the acid is weak or Strong... ??
other than PH???
isnt there any other way??!
thats interesting, i got a whole bunch of different answers
How can u test if the acid is weak or Strong... ??a strong acid would completley dissociate in water
other than PH???
We don't need to know more than this about bond forming and breaking right?
the heat source always has a higher temperature than the surroundinghow do we know if a reaction is endothermic?!
The temp would fall, this is because it takes more energy/heat to break the bonds between the atoms, if it was exothermic, then more energy would be used to form new bonds, and the temp. raises
correct me if im wrong but i thought it was the other way round
cuz endo takes in heat so temp rises(positive)
and exo gives out heat go temp falls(negative)
in a redox reaction heat is not displaced it is either produced or used up
here the temperature is referred to the surrounding not the reagents
so in an exothermic reaction heat is produced which increasaes the temp. of the surrounding so the temperature is increased
u guyssulphur dioxide is a good reducing agent. In the presence of water, it is able to decolourize substances.
"what property of SO2 enables it be used as a bleaching agent?"
thanks!
hey guys,
as the chemsitry exam is on the 1st of june, u must all be revising, and u MUST have some questions,
so if u have any CHEMISTRY questions, post them here and hopefully some one will help.
Gd Luck :)
thank you! :)u guyssulphur dioxide is a good reducing agent. In the presence of water, it is able to decolourize substances.
"what property of SO2 enables it be used as a bleaching agent?"
thanks!
do we need to noe the % of carbon, properties and uses of carbon steels?
and do we need to noe the metals added, properties and uses of alloy steels?
???
so we hav to memorize da percentages and stuff? :(
i was hoping we don hav to :(
hey guys,
as the chemsitry exam is on the 1st of june, u must all be revising, and u MUST have some questions,
so if u have any CHEMISTRY questions, post them here and hopefully some one will help.
Gd Luck :)
Hey Q80BOY
can u plz explain me extraction of aluminium ???
im reallii confused in naming the alcohols...cn summon tll me plz.. ???
i need an explanation..
Thanks..
Here u go.
AHHHH MY REP KEEPS GOING DOWN. WILL THOSE (mind ur vocab)_______ WHO DECREASE REP FOR FUN PLEASE STOP?
AND WILL THE PEOPLE WHO WOULD PROBABLY DECREASE MY REP BECAUSE I JUST SWORE PLEASE GROW UP?
Here u go.+repped u!!!
AHHHH MY REP KEEPS GOING DOWN. WILL THOSE BITCHES WHO DECREASE REP FOR FUN PLEASE STOP?
AND WILL THE PEOPLE WHO WOULD PROBABLY DECREASE MY REP BECAUSE I JUST SWORE PLEASE GROW UP?
@thukon
Thanks.... but m confused...u said dat it can be 2nd or 4th carbon....so how do v kno whch to choose n rite??
@shogun
Thanks...is it necessary dat v count frm the rite...if not then above is my doubt...
my actual doubt..
for example if we have to write the isomers of pentanol:
how will we name this one:
OH
! ! ! !
H-C-C-C-C-H
! ! ! !
-C-
!
look here the OH is either on 2nd and the alkyl group(methyl) is on 3rd.....or OH is on 3rd and the alkyl grp on 2nd.......how to name this???
god i hate this soooo much!!!!
plzzzzz help!!!!
Is this what we were supposed to right, or are we supposed to do something else only?It gives the formula for both the hydrocarbons that are forming the nylon, so i think u have to write the whole structural formula, and not just put boxes.
i think it is the same thing
lol im dumb >:( >:( >:( >:( >:( >:( >:( >:(
but are you sure that we are supposed to do this only and there is nothing else involved?
@thukin
ahaan!!!
:D :D
lollzz...
but still ull use such wrds n ull end up gettin mor -reps...
hahaha lol thukon
anywayz i have a question for everybody
how would u find the percentage of oxygen in a gas jar that contains 150 cm3 of air?
hahaha lol thukonWait, was it a test, or is it ur own genuine doubt, and do these kind of questions appear in IGCSE which means we have to MUG UP THE PERCENTAGES OF DIFFERENT GASES IN THE ATMOSPHERE?!
anywayz i have a question for everybody
how would u find the percentage of oxygen in a gas jar that contains 150 cm3 of air?
hahaha lol thukon
anywayz i have a question for everybody
how would u find the percentage of oxygen in a gas jar that contains 150 cm3 of air?
u like testing others. don't u??
well i believe it is 20% of the volume
that would be 30cm3
now tell us the right ans "LIL" teacher :P
hahaha lol thukonWait, was it a test, or is it ur own genuine doubt, and do these kind of questions appear in IGCSE which means we have to MUG UP THE PERCENTAGES OF DIFFERENT GASES IN THE ATMOSPHERE?!
anywayz i have a question for everybody
how would u find the percentage of oxygen in a gas jar that contains 150 cm3 of air?
hahaha lol thukon
anywayz i have a question for everybody
how would u find the percentage of oxygen in a gas jar that contains 150 cm3 of air?
so any which ways it's 20% of the total volume of air. Any method will do
so any which ways it's 20% of the total volume of air. Any method will do
could be 20% or 21%
here's some problems i had:
1.how do we write overall equations,e.g for habers process?
2. rust prevention-the mechanisms
3.why is a crucible in which magnesium oxide is being made covered with a lid?
4.colour of flame when there is incomplete combustion?
5.what reacts at room temp. with ethanol and ethanoic acid?
A. CaCO3 B.CuO C.CH3OH D.Na
6.what are synthetic macromolecules?
please help!!! ???
vaibhav have a look at the pdf
I have drawn the structure of the nylon
vaibhav have a look at the pdf
I have drawn the structure of the nylon
is it ok if i get the H above the N
like
H
!
...................... . . . . N
here's some problems i had:
1.how do we write overall equations,e.g for habers process?
2. rust prevention-the mechanisms
3.why is a crucible in which magnesium oxide is being made covered with a lid?
4.colour of flame when there is incomplete combustion?
5.what reacts at room temp. with ethanol and ethanoic acid?
A. CaCO3 B.CuO C.CH3OH D.Na
6.what are synthetic macromolecules?
please help!!! ???
1) i dont understand wat u mean!!
2)to prevent rust u could, paint the object, greasing or oiling, plastic coating, chromium plating, galvanizing with zinc, using stainless steel (which is corrosion resistant)
3)depends on the process if ur heating molten or aqueous substances then to prevent the splashing out of materials
4)orange = complete.. blue= incomplete
5) C), i think, cuz its the only organic substance ( ASK SOMEONE ELSE CUZ IM NOT SURE!!)
6)these are man-made polyamide and polyester eg. nylon and terylene
ohh yeah i just realized, if its not methanol, could it be CuO , cuz it can oxidise ethanol into ethanoic acid, right?here's some problems i had:
1.how do we write overall equations,e.g for habers process?
2. rust prevention-the mechanisms
3.why is a crucible in which magnesium oxide is being made covered with a lid?
4.colour of flame when there is incomplete combustion?
5.what reacts at room temp. with ethanol and ethanoic acid?
A. CaCO3 B.CuO C.CH3OH D.Na
6.what are synthetic macromolecules?
please help!!! ???
1) i dont understand wat u mean!!
2)to prevent rust u could, paint the object, greasing or oiling, plastic coating, chromium plating, galvanizing with zinc, using stainless steel (which is corrosion resistant)
3)depends on the process if ur heating molten or aqueous substances then to prevent the splashing out of materials
4)orange = complete.. blue= incomplete
5) C), i think, cuz its the only organic substance ( ASK SOMEONE ELSE CUZ IM NOT SURE!!)
6)these are man-made polyamide and polyester eg. nylon and terylene
Lil wayne, uve got the flames mixed up. Blue is complete. Red or orange is incomplete.
The answer is not C for the other thing. I m sure, because C is methanol. Im pretty sure methanol and ethanol dont react at room temp, but i dont know the answer.
wait a min...
twilight said that red/orange in case of incomplete combustion....
lilwayne says:orange for complete combustion..
so now whch one is correct??
here's some problems i had:1.N2(g) + 3H2(g) 2NH3(g).
1.how do we write overall equations,e.g for habers process?
2. rust prevention-the mechanisms
3.why is a crucible in which magnesium oxide is being made covered with a lid?
4.colour of flame when there is incomplete combustion?
5.what reacts at room temp. with ethanol and ethanoic acid?
A. CaCO3 B.CuO C.CH3OH D.Na
6.what are synthetic macromolecules?
please help!!! ???
its Na whch reacts with ethanol and ethanoic acid at room temperature...
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??Yeah lilwaynes right. Its one of those unexplainable things youd probably only learn why in college.
LoL..!!why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??
because thats what the scientists found out when they did tests on them, lol
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??Yeah lilwaynes right. Its one of those unexplainable things youd probably only learn why in college.
@nid. What do sodium and ethanol form when reacted? And sodium and ethanoic acid?
OMG ALKOXIDE?? IM GONNA DIE NOW. but whatever as long as its not in our syllabus. I figured out the sodium ethanoate while waiting for a response, but what about the other 3? U said it reacts with A B C and D.
AFK for real now bye.
Okay,, I am sort of confused .. umm.. do we have to know about the Faraday Constant and all for Chemistry? as in ..in calculations in electolysis ..not for chem but for physics.......so chill 8)
because I sort of just checked the syllabus.. couldnt find anything in it .. but its in my book .. n well its a cambridge one =S ..and though i know there are loadsa stuff in it which aint in the syllabus but i our teacher still tells us to study stuff to be on the safe side.. but i honestly dont have time to study all tht.. so pleaseee anyone tell me if they are iN!
ok, here's a question from me: how do you make soda lime glass? (no looking at the book! ;))
ok, here's a question from me: how do you make soda lime glass? (no looking at the book! ;))
ok, here's a question from me: how do you make soda lime glass? (no looking at the book! ;))
hey guys wassup?1) cuz when force is applied, the ion layers slip, but the delocalized electrons move into new positions preventing shattering
ok i hav a few questions
1-how does the structure of metal explain why it is malleable?
2-suggest an explanation why exposure to atmospheric pollution changes basic lead (11)carbonate into lead(11)sulphate
3-ethanol can be made from starch.this can be broken down by enzymes to simple sugars with formulae of the type shown
ho-(box)-oh
what other method changes starch into simple sugar?
sum1 help me
hey guys wassup?
ok i hav a few questions
1-how does the structure of metal explain why it is malleable?
2-suggest an explanation why exposure to atmospheric pollution changes basic lead (11)carbonate into lead(11)sulphate
3-ethanol can be made from starch.this can be broken down by enzymes to simple sugars with formulae of the type shown
ho-(box)-oh
what other method changes starch into simple sugar?
sum1 help me
i cannot thank you both enogh u too NID404!!!!!!!!hey guys wassup?1) cuz when force is applied, the ion layers slip, but the delocalized electrons move into new positions preventing shattering
ok i hav a few questions
1-how does the structure of metal explain why it is malleable?
2-suggest an explanation why exposure to atmospheric pollution changes basic lead (11)carbonate into lead(11)sulphate
3-ethanol can be made from starch.this can be broken down by enzymes to simple sugars with formulae of the type shown
ho-(box)-oh
what other method changes starch into simple sugar?
sum1 help me
2)because atmospheric pollution may contain sulphuris acid( in acid rain) which reacts with the lead(II) carbonate forming
lead(II) sulphate + water + carbon dioxide
3)by acid hydrolysis ( boiling the starch with acid)
ok, here's a question from me: how do you make soda lime glass? (no looking at the book! ;))
hahaha, wats soda lime glass, i know hot to make glass, but not soda lime glass!!!!!!!!!!!
for glass: add limestone, sand and soda (if thats wat u mean by soda lime glass) to a very hot furnace
the materials react together, and form a hot liquid, and then the liquid is removed and shaped into many different products
ok, here's a question from me: how do you make soda lime glass? (no looking at the book! ;))
hahaha, wats soda lime glass, i know hot to make glass, but not soda lime glass!!!!!!!!!!!
for glass: add limestone, sand and soda (if thats wat u mean by soda lime glass) to a very hot furnace
the materials react together, and form a hot liquid, and then the liquid is removed and shaped into many different products
soda lime glass is made by reacting limestone, sand and sodium carbonate together with the glass to be recycled at 1500oC.
your answers was pretty close.
@nid - yeah, it's the time to sit back and enjoy some soda pop!
@ kim. just take the average in a kind of way. If u know what i mean.
@ nid. Thanks a lot. I guess u logged off but ill ask anyway so anyone can reply. All simple sugars are called glycols? And do complex sugars like starch have any special names? or can i call them polymers?
hey u guyz know those questions where they give the boiling points of sum alkanes and then ask to predict the boiling pt of one of them
how do u dat?
hey u guyz know those questions where they give the boiling points of sum alkanes and then ask to predict the boiling pt of one of them
how do u dat?
@ kim - to find the boiling point there r 2 cases -
1) they give u graph to draw and u have to predict the boiling point - in that case u have to continue the graph line in the same trend and read the value on the graph (known as extrapolation)
2) they give u table and tell u to predict the boiling point - then 4 sure there will be some linear trend shown by the boiling points given in the table.
hope u understand
@thukon - simple sugars like glucose and sucrose are called monosaccharides
maltose and fructose are "bigger" molecules known as disaccharides
starch and cellulose are complex molecules known as polysaccharides
Questions :1) used to make PVC (chlorine) , used in toothpaste(flourine)
1) wha are the 2 uses of the 5 halogen atoms ??
2) explain by giving its structure why diamond is so hard ?? [4]
3) explain the structure of Diamond ??
4) describe the structure of germanium ?
the 2 uses of the 5 halogen atoms - that's a strange question. sorry, dunno the answer
diamond is so hard because the atoms are tightly held together in a tetrahedral structure. the inter molecular forces (van der waal's forces) is very very strong, hence it is so hard and rigid. the atoms are not arranged in layers, so it cannot slip over each other.
the structure of germanium is very similar to that of carbon (tetrahedral)
ehhh ..
what about silicon does it has anything to do with Diamond ??
in question 1 >> i mean to say that Give 2 uses for each halogon atom ? like : a question came in the year 1996 that give 2 uses of Bromine and Iodine ?
so it thought it is better to know 2 uses for each halogen atoms .
Questions :
1) wha are the 2 uses of the 5 halogen atoms ??
2) explain by giving its structure why diamond is so hard ?? [4]
3) explain the structure of Diamond ??
4) describe the structure of germanium ?
Sulphur reacts violently with magnesium to form the ionic compound magnesium
sulphide. Draw a diagram that shows the arrangement of the valency electrons in this
compound.
Use O to represent an electron from a magnesium atom.
Use X to represent an electron from a sulphur atom. [3]
Please do this
can someone help me understand the difference between evaporation and crystallization? and when you would use each one ?
how do you know what is the suitable reagents for certain reactions ??
If they ask me do describe the structure of Diamond >>> I can either say : " It has tetrahydral shap with four carbon atoms convalently bonded to other four carbon forming a gaint marcomolecular shap "
OR
" It has tetrahydral structure with four oxygen atoms covalently bonded with a single atom of Silion forming a gaint marcomolecular shap "
plz find it attached
Mg ? Mg2+ + 2 e-
S + 2e- ? S2-[
how did magnesium chloride come in the picture..
i think it was sulphide
anyway
the second question answer
visi the link and chk out "untitled1"
hey hii nid,,
ur brain is really messed up because its sulphide..not sulphate...
and thanks for the tip
will remember it for the exam..lol
help me
i am sgvaibhav
i banned myself
???
i was going to do it for 0.1 day, but i did it for 1 days.
xD help me :-X
1) thallium(1)hydroxide has a similar chemical property to sodium hydroxide .
i) Given 0.1mol/dm^3 solution of thallium(1)hydroxide and of ammonia , describe how you could show that thallium(!) hydroxide is the stronger base .
-----------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------- [3]
( i think we have to Add universal indicator .. but what the heck .. four lines !! I tihnk we have to write about thier colours changes and PH . I dont know
1) thallium(1)hydroxide has a similar chemical property to sodium hydroxide .
i) Given 0.1mol/dm^3 solution of thallium(1)hydroxide and of ammonia , describe how you could show that thallium(!) hydroxide is the stronger base .
-----------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------- [3]
( i think we have to Add universal indicator .. but what the heck .. four lines !! I tihnk we have to write about thier colours changes and PH . I dont know
At the same concentration the stronger base has a higher pH.(check with indicator)
At the same concentration the stronger base has a better conductor of electricity.
hey ManaH .. okay .. im just anssering ur first one.. because the rest needs calculation and im too lazy to do that!
Disposal of polymers in their landfill sites.. as they are non-biodegradable .. first takes up space .. causes sight pollution ...
and burning it leads to emission of harmful oxides such as oxides of nitrogen .. or carbon monoxide.. which are both harmful ..
(as nitrogen monoxide leads to ozone formation in the lower hemisphere .. guess.. thts wht its called and well carbon monoxide
is a poisonous gas .. harmful for health.. ) and lastly mht also lead to global warming.. as increases emission of carbondioxide into the atmosphere..imbalancing the carbon cycle..
hey,
umm can some clearify my doubts:)
1)
Q)descirbe the polltuion prblems caused by the disposal of polymer in ther landfills sites n by buring?
2)(c) Each tablet contains the same number of moles of CaCO3 and MgCO3. One tablet
reacted with excess hydrochloric acid to produce 0.24 dm3 of carbon dioxide at r.t.p.
CaCO3 + 2HCl ? CaCl2 + CO2 + H2O
MgCO3 + 2HCl ? MgCl2 + CO2 + H2O
(i) Calculate how many moles of CaCO3 there are in one tablet.
number of moles CO2 = ..............(0.01)
number of moles of CaCO3 and MgCO3 = ..............(0.01)
number of moles of CaCO3 = ..............(0.01)
(ii) Calculate the volume of hydrochloric acid, 1.0 mol /dm3, needed to react with one
tablet.
number of moles of CaCO3 and MgCO3 in one tablet = ..............(0.02)
Use your answer to (c)(i).
number of moles of HCl needed to react with one tablet = ..............(0.02)
volume of hydrochloric acid, 1.0 mol /dm3, needed to
react with one tablet ..............(0.02)
he brackets are my anser cans ome one help?:)
Omg i am so proud of myslef i finally got stichromatery*dances arund the house*hey,
umm can some clearify my doubts:)
1)
Q)descirbe the polltuion prblems caused by the disposal of polymer in ther landfills sites n by buring?
2)(c) Each tablet contains the same number of moles of CaCO3 and MgCO3. One tablet
reacted with excess hydrochloric acid to produce 0.24 dm3 of carbon dioxide at r.t.p.
CaCO3 + 2HCl ? CaCl2 + CO2 + H2O
MgCO3 + 2HCl ? MgCl2 + CO2 + H2O
(i) Calculate how many moles of CaCO3 there are in one tablet.
number of moles CO2 = ..............(0.01)
number of moles of CaCO3 and MgCO3 = ..............(0.01)
number of moles of CaCO3 = ..............(0.01)
(ii) Calculate the volume of hydrochloric acid, 1.0 mol /dm3, needed to react with one
tablet.
number of moles of CaCO3 and MgCO3 in one tablet = ..............(0.02)
Use your answer to (c)(i).
number of moles of HCl needed to react with one tablet = ..............(0.02)
volume of hydrochloric acid, 1.0 mol /dm3, needed to
react with one tablet ..............(0.02)
he brackets are my anser cans ome one help?:)
1. in landfill sites they cause visible pollution and burning releases toxic gases. remember to write toxic or poisonous not harmful
2.i)correct
ii)correct
I think that these are the answers but im not sure:
nov 2000 Q1)
d) 0.167 mol
1.6 mol
0.267 mol
15.03g
79.8%
I hope this helps ;)
what is stochiochemitry or something like that?Stochiochemitry is something that has to do with moles.
hey,
umm can some clearify my doubts:)
1)
Q)descirbe the polltuion prblems caused by the disposal of polymer in ther landfills sites n by buring?
2)(c) Each tablet contains the same number of moles of CaCO3 and MgCO3. One tablet
reacted with excess hydrochloric acid to produce 0.24 dm3 of carbon dioxide at r.t.p.
CaCO3 + 2HCl ? CaCl2 + CO2 + H2O
MgCO3 + 2HCl ? MgCl2 + CO2 + H2O
(i) Calculate how many moles of CaCO3 there are in one tablet.
number of moles CO2 = ..............(0.01)
number of moles of CaCO3 and MgCO3 = ..............(0.01)
number of moles of CaCO3 = ..............(0.01)
(ii) Calculate the volume of hydrochloric acid, 1.0 mol /dm3, needed to react with one
tablet.
number of moles of CaCO3 and MgCO3 in one tablet = ..............(0.02)
Use your answer to (c)(i).
number of moles of HCl needed to react with one tablet = ..............(0.02)
volume of hydrochloric acid, 1.0 mol /dm3, needed to
react with one tablet ..............(0.02)
he brackets are my anser cans ome one help?:)
1. in landfill sites they cause visible pollution and burning releases toxic gases. remember to write toxic or poisonous not harmful
2.i)correct
ii)correct
how can u calculate the mass of one mole of C8 alcohol. Huh?Huh??
plz help
Omg i am so proud of myslef i finally got stichromatery*dances arund the house*
about the harmful ya i know i read the xmainer comment sayin gits not harmful write
TOXIC/ Posioniustnx anyways:)
rep (+)
HELP REQUIRED EXPERT PEOPLE!
Please solve Question 5 of Chem P3 May/June 2002.
No guesses please, because we cannot find a relevant markscheme.QuotePLEASE ANSWER THE QUESTION ASKED UP, AS IF YOU ARE WRITING MODEL ANSWERS BY CIE.
Thanks
HELP REQUIRED EXPERT PEOPLE!
Please solve Question 5 of Chem P3 May/June 2002.
No guesses please, because we cannot find a relevant markscheme.
Can any one make a mnemonic for the reactivity series containing:
K
Na
Ca
Mg
Al
C
Zn
Fe
Pb
H
Cu
Hg
Ag
Pt
Au
If you already know one please tell im having a lot of difficulty remembering this one.
I cant memorize the action of heat on Hydroxides, Nitrates and Carbonates too.
Im not really the mug up type lol
Please help!
QuoteHELP REQUIRED EXPERT PEOPLE!
Please solve Question 5 of Chem P3 May/June 2002.
No guesses please, because we cannot find a relevant markscheme.QuotePLEASE ANSWER THE QUESTION ASKED UP, AS IF YOU ARE WRITING MODEL ANSWERS BY CIE.
Thanks
Waiting....
Can any one make a mnemonic for the reactivity series containing:
K
Na
Ca
Mg
Al
C
Zn
Fe
Pb
H
Cu
Hg
Ag
Pt
Au
If you already know one please tell im having a lot of difficulty remembering this one.
I cant memorize the action of heat on Hydroxides, Nitrates and Carbonates too.
Im not really the mug up type lol
Please help!
some one please help !!!
can some one please solve paper3 O/N 2002 Q1 part (iv) ? please and state how u did it ?
and also the same year paper 3 Q3 part (f) all parts and explain how u did it ? please
some one please help !!!
can some one please solve paper3 O/N 2002 Q1 part (iv) ? please and state how u did it ?
and also the same year paper 3 Q3 part (f) all parts and explain how u did it ? please
dude
question 1)a) only has like 3 parts
some one please help !!!
can some one please solve paper3 O/N 2002 Q1 part (iv) ? please and state how u did it ?
and also the same year paper 3 Q3 part (f) all parts and explain how u did it ? please
plz......can i have them manah!!!!sure cheak ur inbox:)
my id:tascorp20@gmail.com
thanx u sent me 3 times!!!!!!!!!!!!!!!!cooooooooooooolthey are three different thing
can some one give me mark scheme for November 2003 paper3 ? the one on Free exam paper is totally unrelatedthere u go :D
u guys,
for exothermic: we say the temp increases
and endothermic: the temp decreases
rite?
so this is abt the surrounding and not the reagent?
pls help!
u guys,When the reaction is endothermic.... The surroundings will cool down...e.g. the beaker may cool down....
for exothermic: we say the temp increases
and endothermic: the temp decreases
rite?
so this is abt the surrounding and not the reagent?
pls help!
Guyz how do I make the structural Formula.....(i know the formulas themselves but not the structural formulas....thanks.
Tell me which one... and do tell me if ur sure or not....
I think wehave to use number 2 but i'm not sure...
On the picture I drew....
1. Structural formula (lewis structure)
2. Also structural formula (different type) (text structure)
3. Skeletal formula
4. Chemical formula
1 & 2 both are structural formulas...
But in the exam when they ask for structural formula do i draw number 1 or number 2???
i.e. text structural formula or lewis structural formula????
Thanks in advance
THEIGBOY
By the way if there is need for any ppapers or marking schemes do tell me... i have most, if not all of them from 1999 onwards....AND[/shadow][/glow][/color][/font]GOODBESTEST OF LUCK!!!!!!!!!!!!
(i know there is no such word as "bestest" but still...)
emi
0.01 moles of CO2 were produced from the total reaction
the tablet has the same no. of moles of CaCO3 and MgCO3
so the no. of moles of CaCO3 and MgCO3 is 0.01 moles also
the no. of moles of CaCO3 only is 0.01/2 = 0.005
moles of HCl=0.01x4
no.=V x C
0.04=V x 1
V=0.04 dm3=40cm3
nope nid ur wrong
emi
0.01 moles of CO2 were produced from the total reaction
the tablet has the same no. of moles of CaCO3 and MgCO3
so the no. of moles of CaCO3 and MgCO3 is 0.01 moles also
the no. of moles of CaCO3 only is 0.01/2 = 0.005
moles of HCl=0.01x4
no.=V x C
0.04=V x 1
V=0.04 dm3=40cm3
i think uve mistaken
CaCO3+ 2HCl--->CaCl2+CO2+H2O
same with MgCO3
so ratio of metal carbonate to Carbon dioxide is the same(1:1) for each of the carbonates, so each one is 0.01mol
so if no of moles of CO2is 0.01 then no. of moles of CaCO3 is also 0.01
and
conc=mol/dm3
no of moles of HCl is 0.02 because mole ratio is 1:2(CaCO3+2HCl)
so if metal carbonate is 0.01, HCl is 0.01x2=0.02
1mol/dm3= 0.02/vol
volume=0.02/1
=0.02dm3or 20cm3
i am getting confused about the term structural formula
because in one question we have to draw the structural formula
so my answers was
NH2-NH2
In markscheme
H H
| |
N- N
| |
H H
nov 2008 chem p3 was DA EASIEST EVER.........I HOPE IT COMES LIKE THAT THIS TIMEthat was the one i did :P
Question on a past paper: on the October/November 2006 paper 3, question 8 ciii)...@idol2009
It shows the formulas of 2 fats, and asks you how you would distinguish between the 2 fats, and asks you for the test and results.
Well, i thought it was pretty obvious it was the bromine test, but i wasn't quite sure how to tell which compound was saturated and which one was unsaturated..?
I'd appreciate it if anyone could help =)
wat my teacher said,more saturated means more hydrogenSaturated is where the bondings are all single....i.e. no double or triple bonding.
guyz please help me with this part of the syllabus....Potassium manganate(VII) to manganese(II) salt--purple to colorless (reduction (7 to 2))
"identify redox reactions by changes in
oxidation state and by the colour changes
involved when using acidified potassium
manganate(VII), and potassium iodide."
Please tell me everything i shud know about this
Thanks...
THEIGBOY
Suggest an explanation why Butan-1-ol cannot form long polymer molecules but ethane-1,2-diol can.
2 marks
very hard :'( :'(
Suggest an explanation why Butan-1-ol cannot form long polymer molecules but ethane-1,2-diol can.Look
2 marks
very hard :'( :'(
Suggest an explanation why Butan-1-ol cannot form long polymer molecules but ethane-1,2-diol can.
2 marks
very hard :'( :'(
very hard :'( :'(
professionals need ur help
Suggest an explanation why Butan-1-ol cannot form long polymer molecules but ethane-1,2-diol can.Just finished making the picture,here it is...
2 marks
very hard :'( :'(
Thanks alotguyz please help me with this part of the syllabus....Potassium manganate(VII) to manganese(II) salt--purple to colorless (reduction (7 to 2))
"identify redox reactions by changes in
oxidation state and by the colour changes
involved when using acidified potassium
manganate(VII), and potassium iodide."
Please tell me everything i shud know about this
Thanks...
THEIGBOY
Potassium iodide to iodine--colorless to brown( 2I-to I2(oxidation))
EDIT:---> sorry forgot to put arrow between first and second diagram of ethane-1,2-diolSuggest an explanation why Butan-1-ol cannot form long polymer molecules but ethane-1,2-diol can.Just finished making the picture,here it is...
2 marks
very hard :'( :'(
Hope it explains everything u want to know
By the way... +rep me if it helps
SMARTThanks
+REP
thanks igboyMy pleasure
can anyone give me list of:I had a paper including all these but its lost :( Someone provide us with it
1)soluble carbonates and the insoluble ones
2)insoluble alkalis, and soluble ones
3)soluble oxides and insoluble ones
4) amphotric oxides
hey wt is exactly the definition of "equilibrium" for reversible rxns? ???
Umm..okay..I'm not sure I really get it..
I know that unsaturated compounds contain carbon-carbon double bonds, but none of these contain double bonds...
and you said that the formula for saturated compounds is CnH 2n+1, but aren't alkanes saturated compounds, and that's not their formula..right?
and alkenes are unsaturated and their formula is CnH 2n,
? i hope I haven't confused you and myself even more
hey wt is exactly the definition of "equilibrium" for reversible rxns? ???
can anyone give me list of:
1)soluble carbonates and the insoluble ones
2)insoluble alkalis, and soluble ones
3)soluble oxides and insoluble ones
4) amphotric oxides
I believe both are the same-giant and macroits not a question...i just need da meanings... ;D
can u give me the exact question. w8 hybye said was right in a way. if your talking about giant covalent molecules then it's diamond, silica,graphite
germanium is an element so that is wrong
u guys,When the reaction is endothermic.... The surroundings will cool down...e.g. the beaker may cool down....
for exothermic: we say the temp increases
and endothermic: the temp decreases
rite?
so this is abt the surrounding and not the reagent?
pls help!
When the reaction is exothermic..... the surrounding will heat up..... e.g. the beaker may heat up....
and yes...they are talking abt the surroundings....
@thukon ---->
Carbon comes after aluminium and before zinc...hope it helps
hey wt is exactly the definition of "equilibrium" for reversible rxns? ???
when the rate of forward and backward reaction is same, and their concentation of products and reactants does not change
a time when the forward reaction rate and the reverse reaction rates are equal. The mixture is at equilibrium.hey wt is exactly the definition of "equilibrium" for reversible rxns? ???
u guys, is equilibrium "when forward rxn is equal to the backward rxn" or the "conc. of reactant is equal to the products"
i dont get it :( pls help!
Umm..okay..I'm not sure I really get it..
I know that unsaturated compounds contain carbon-carbon double bonds, but none of these contain double bonds...
and you said that the formula for saturated compounds is CnH 2n+1, but aren't alkanes saturated compounds, and that's not their formula..right?
and alkenes are unsaturated and their formula is CnH 2n,
? i hope I haven't confused you and myself even more
hey wt is exactly the definition of "equilibrium" for reversible rxns? ???
when the rate of forward and backward reaction is same, and their concentation of products and reactants does not change
thanks :)
+rep
Cation reactivity series:
Please-K
sent-Na
cats-Ca
monkeys-Mg
and-Al
zebras-Zn
in-Fe
large-Pb
hired-H
cages.-Cu
Make-Hg
sure-Ag
padlocked.-Pt
can some one give me mark scheme for November 2003 paper3 ? the one on Free exam paper is totally unrelated
ricko the one u posted was for 2005 i want 2003
Give
examples
of Oxidising agent and Reducing Agnet
Test for Oxidising agent
the thing is that if u see that markscheme and match it with the Question paper if doesnt match at all .. in Question paper the first Questions talk about liquid fuels obtained from petroleum while in the mark scheme it says 1) different boiling points ??
part b) says magnesium carbonate reactions with HCL to form a salt name that salt
the markscheme says Volume decreases for forward reaction.
what i mean is that its not related at all
Guys how do we do Question " 7 a) i) " on Paper 3 November 2008[/b][/color]
The volumes one
can someone give me the steps as well
ok is it 1st varient or seocnd varientGuys how do we do Question " 7 a) i) " on Paper 3 November 2008[/b][/color]
The volumes one
can someone give me the steps as well
is this da 1st varient or da 2nd if its 2nd then ur ans is wrong ,manahits 1st vareint
Hey! Can anyone help me with question 6cii november 03 p3 ??
Thank youu
A classmate told me a good mnemonic for the reactivity series, but it goes by the first letter of the elementaddition of carbon and Platinum and its like this
Please- Potassium
Send- Sodium
Lord- Lithium
Charles- Calcium
McClain- Magnesium
A- Aluminium
Zebra- Zinc
If- Iron
The- Tin
Lame- Lead
Horse- Hydrogen
Cannot- Copper
Munch- Mercury
Sweet- Silver
Grass- Gold
No point in adding one for platinum, because it goes at the end anyway. Where does carbon go in this?
@aquarian. In exothermic, more heat is given out than taken in by the reaction. In endothermic, more heat is taken in than given out.
ok, i have a question, see:
1) how can i show in caculation tht a substance is in excess?
2)why to make alloys with metal is better than making with non metals?
3)y do sientist believe tht no undiscovered eliment is missing from the periodic table?
and By the way Thanks emi..
i need help wid question 3 c the 2nd part.
chem p3 oct 2008
anyone care to help? i dont get it.
thanks
i need help wid question 3 c the 2nd part.
chem p3 oct 2008
anyone care to help? i dont get it.
thanks
hahaha nid,,
answered both of themm
was abt to do that..
lol.. :)
heyyyy....
i need help and May June 06 q.6
The radioactive isotopes!
help help help
i have 9 more hours before exams ???
heyyyy....
i need help and May June 06 q.6
The radioactive isotopes!
help help help
i have 9 more hours before exams ???
Radioactive Isotopes:
uses:
Medical (CIGS - cigarettes :P)
C Cobalt Co 60 - Inaccessible cancer
I Iodine I 131 - Thyroid
G Gamma Rays - Sterilising
S Strontium Sr 90 - Skin cancer
IndUStrial
Uranium U 235 - nuclear power
Strontium Sr 90 - thickness of paper
hope i helped :)
really, i need help with the question of excess stuff in, oct/nov2007 Q(7bii)
really need to know how to do it. ??? :'( :-[
Is the pressure for the Contact Process 10 atm or 20 atm, cuz the mark scheme says 10 but the book says 20 :S
Is the pressure for the Contact Process 10 atm or 20 atm, cuz the mark scheme says 10 but the book says 20 :S
huh we learnt it was 1 atp not 10 or 20 n i checked wikipedia too they say its 1-2 atp so the rite answer is 1 atmospheric pressure
@shogun. CaCO3= 40+12+16+16+16= 100
Number of moles of CaCO3 = 0.3/100= 0.003
Number of moles of HCL = 1 mol per dm3, and 1000cm3 = 1 dm3. 5/1000= 0.005
The reaction needs 1 mol of CaCO3 and 2 mols of HCl. So the HCl needs to be double the the CaCO3, but here there isnt enough, because the CaCO3 is 0.003, and the HCl needs to be 0.006, but its only 0.005. So CaCO3 is in excess.
I was kinda confused myself doing the question. Check with the mark scheme and tell me if im correct. If i am, +rep me PLZ. I REALLY NEED IT!!
@shogun. CaCO3= 40+12+16+16+16= 100
Number of moles of CaCO3 = 0.3/100= 0.003
Number of moles of HCL = 1 mol per dm3, and 1000cm3 = 1 dm3. 5/1000= 0.005
The reaction needs 1 mol of CaCO3 and 2 mols of HCl. So the HCl needs to be double the the CaCO3, but here there isnt enough, because the CaCO3 is 0.003, and the HCl needs to be 0.006, but its only 0.005. So CaCO3 is in excess.
I was kinda confused myself doing the question. Check with the mark scheme and tell me if im correct. If i am, +rep me PLZ. I REALLY NEED IT!!
here it is
(ii)one piece of marble 0.3g, was added to 5cm3 of hydrochloric acid, concentration 1.00 mol/dm3. which reagent is in excess? give reason for your answer.
mass of one mole of CaCO3 =100g
number of moles of CaCO3= .................................................................
number of moles of HCl=.......................................................
regent in excess is ...........................................................
reason....................................................................
[4]
(iii) use your answer to (ii) to calculate the maximum volume of carbon dioxide produced measured at r.t.p.
...[1]
explain to me what u have to do, plz dont just give me the answer, do explain every part on how to find the excess.
Thanks
CAn u plz guys tel me what the hell does the "catalytic converter" do????????????????????
plz tel me evrythng abt it..
I really need help :'( :'( :'( :'( :'( :'(
People i have found this site .....Hope its useful..... http://www.chemactive.com/grade_10.html :P
People i have found this site .....Hope its useful..... http://www.chemactive.com/grade_10.html :P
hey thanks +rep.... ur first ;D
@ibiza a little needs to be corrected with the catalytic converter. it converts carbon monoxide to carbon dioxide and oxides of nitrogen to nitrogen(not nitrogen dioxide)
u guys...help me with this question..
ppr3 june 04 7 b) ii
People i have found this site .....Hope its useful..... http://www.chemactive.com/grade_10.html :P
hey thanks +rep.... ur first ;D
@ibiza a little needs to be corrected with the catalytic converter. it converts carbon monoxide to carbon dioxide and oxides of nitrogen to nitrogen(not nitrogen dioxide)
Ok look u dnt get.. do u like heat it with excess oxygen so it can turn from CO to CO2??
u guys...help me with this question..
ppr3 june 04 7 b) ii
can someone answer tht
i need help with that too
i was talking about bii
how many moles of hydrogen formed
and thx By the way
+rep 4 u
acid+base= salt + water
acid+carbonate=salt + water +carbon dioxide
as the oxide is basic
the salt is sodium benzoate
gettit?
i just hope im right
correct me if im wrong tho
acid+base= salt + water
acid+carbonate=salt + water +carbon dioxide
as the oxide is basic
the salt is sodium benzoate
gettit?
i just hope im right
correct me if im wrong tho
Oh i see
I dint know sodium benzoate was a salt lol ;D
i need help in nov 2004 q7number of moles of Fe2(SO4)3 = 1/40 or 0.025
c)
heywhich year?
can sm1 plz attatch the mark scheme
fr o/n session 2003 chemistry paper 3??
:-[
argh...sumbudy decreased my rep even more
argh...sumbudy decreased my rep even more
frget rep man
it dsnt mke a differnc
do u hav the mark scheme?? :-[
argh...sumbudy decreased my rep even more
frget rep man
it dsnt mke a differnc
do u hav the mark scheme?? :-[
Which year????
i have all marking schemes from 1999 onwards
i need help in nov 2004 q7number of moles of Fe2(SO4)3 = 1/40 or 0.025
c)
number of moles of Fe2 O3 formed = 1/40 or 0.025
mass of iron(III) oxide formed = 0.025 x 160 = 4g
number of moles of SO3 produced = 3/40 or 0.075
volume of sulphur trioxide at r.t.p. = 0.075 x 25
= 1.8dm3
hope it helps
why do u multiply 0.075 by 25?
and can u attatch p3 1999 mark scheme and que paper
+rep
By the way guyz my rep got reduced.... may i know who did it and why????
go to www.drop.io/theigboyargh...sumbudy decreased my rep even more
frget rep man
it dsnt mke a differnc
do u hav the mark scheme?? :-[
the password is in ur inbox....
and download the file... i can't upload it here for some reason...
Which year????
i have all marking schemes from 1999 onwards
2003
HEYYYY GUYSSS!!!!!!!! PLEASE SOMEONE HELP ME?!
Okay, for Organic chemistry, when they ask you for a starch molecule or sugar molecule... My book gives you a very comlex structure that sort of looks like a crab or..a extented hexagon, with OH-O and H..
But the past paper June 2008 marking scheme (its hard to understand what they want us to give) but a simple square with just an -O- on either side! Really would appreciate it guys!
Good luck! By the way when do u guys have ur exam..? I have mine in about 11 hours.. WOOOT!!!!! **cofffeeee time*****************
In drawing an alloy, do we draw the different cations with different colors(shade one) or different sizes??? plz reply
In drawing an alloy, do we draw the different cations with different colors(shade one) or different sizes??? plz reply
Different sizes and shaded I think. But most probably different sizes.
Please help: in October/November 2004, Q6b i) Why do we get -OOC-C6H4-COOCH2CH2O-
Please someone tell me why do we put the O (in bold) after the CH2CH2, shouldn't we just continue with COO bond? Please help
And, Q8c iii) please help how to work out the answer.
Thanks in advance.
when lactic acid is heated, u get acrylic acid and ..............................??water
for me it was horrible or amazingg! it was in between :( hope we all did well tho!
hey can any1 who has done the paper tell me what was the formula and reasoning to the phosphate of T metal question.otherwise i guess the paper rocked!
hey guys,
please wait for 24hrs and then discuss the exam,
thanks :)
ManaH, it's impossible this year to have the gardethresholds are going to be like this, in MJ08 the exam was SO easy and it was like 58/80 is an A!! So how come in a diffiuclt exam like this?In MJ08 The A was 45/80
i hope its lower than 45 this year :)
hey ya....i du as a matter of fact....pm me ur email...i ll send it across 2 u :)thankyou so mcuh cheak ur messages
my friend tought me an easier way to study these...luk up^^^^
HOPES THIS HELPS :D
i have another interesting one:but
Please Potassium
Send Sodium
Cows Calcium
Monkeys Magnesium
And Aluminium
Zebras Zinc
In Iron
Large Lead
Hard Hydrogen
Cages with Copper
Maximum Mercury
Security Silver
Guards Gold
Haha.....lol...again...THE REACTIVITY SERIES!!!!!!!!
ohh ya!!thats for physics..
i got one i guess i guess |AM| might remeber covering it wid lid and lagging and all those stuff in specific heat capacity qus!!
confusion!..how do u obtain crystals from a solution of CuSO4?..evaporate it?/heat it?..nd y?
By the way...u guyz missed the working of hydrogen fuel cells with acid electrolyte..
heres. it..
the hydrogen (H2) loses electrons.. 2H2 --> 4H+ + 4e- which travel through the circuit to the cathode and react with O2..also the H+ ions from the acid electrolyte meets the electrons and O2 at the cathode
the reaction
O2 + 4H+ + 4e- = 2H2O
---
The H+ ions removed from the electrolyte are replaced by those produced at the anode.
@adorabledaughter - yea..ut u can use the word heat and crystallization point.
Please Potassium
Send Sodium
Cows Calcium
Monkeys Magnesium
And Aluminium
Caribbean Carbon
Zebras Zinc
In Iron
Large Lead
Hard Hydrogen
Cages with Copper
Maximum Mercury
Security Silver
Guards Gold
please... Platinum
i gues we must change the last thig
we can not have two please...
lolzzz :D :D
so i have made it to
Please Potassium
Send Sodium
Cows Calcium
Monkeys Magnesium
And Aluminium
Caribbean Carbon
Zebras Zinc
In Iron
Large Lead
Hard Hydrogen
Cages with Copper
Maximum Mercury
Security Silver
Guards to Gold
pune Platinum
lolzzz..... :D :D :Dloll....wud be nice eh? if poss.
guys do u like intend to combine all chemistry in one single mnemonic?????????? ;D ;D ;D :P :P ;)
i guess we must leanr all the subject in same way!!!yea lol... makes learnin soo much simpler!! :D
My teacher used this one:
Popular= potassium
Scientist= Sodium
Can= Calcium
Make= magnesium
A= aluminium
Zoo= zinc
In= iron
The= tin
Low= lead
Country= copper
Side= silver
Kinda lame but I remember it better. just the gold and platinum missing... :-\
k..!
do it soon!!
K..will tryI LIKE IT! :P
to start with Cations are pawsitive.
ANION is A Negative ION
:D
will make some for the tests soon
K..will try
to start with Cations are pawsitive.
ANION is A Negative ION
:D
will make some for the tests soon