IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: J.Darren on May 31, 2010, 04:19:25 am
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Organic Chemistry
Fuels :
- Coal
- Natural gas (Methane)
- Petroleum (Crude oil)
Fractional distillation:
N/A - Refinery gas (used as a fuel)
30 degree celsius - Gasoline (used as a fuel in cars)
110 degree celsius - Naphtha (used as make chemicals)
180 degree celsius - Kerosene / Paraffin (used as a fuel in jet engines)
260 degree celsius - Diesel oil / Gas oil (used as a fuel in diesel engines)
N/A - Fuel oil (used as a fuel for ships and for home heating systems)
N/A - Lubricating oil (used in waxes and polishes)
N/A - Bitumen (used as a fuel in jet engines)
Homologus series :
- Trend in physical properties
- Same general formula
- Same functional group
- Similar chemical properties
- Differs from its neighbouring member by CH2
Properties of Alkanes :
Saturated hydrocarbons
General formula : CnH(2n+2)
Increase in boiling point
Physical state at room temperature : Gas > Liquid > Solid
Combustion of alkanes :
Gives CO2 and water, incomplete combustion will give CO and water.
Subsitution reaction :
Condition - Bright light (Photochemical)
Alkanes react with chlorine to give a mixture of chloroalkanes. One hydrogen atom is subsituted by one chlorine atom.
Methane + Chlorine -> Chloromethane (CH3Cl) + HCl
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Properties of Alkenes :
Unaturated hydrocarbons
General formula : CnH2n
Alkenes are made by cracking alkanes. Long alkene molecules are passed over a heated catalyst consisting of Silicon (IV) Oxide and Aluminium Oxide.
C10H22 -> C8H18 + C2H4
Decane -> Octane + Ethene
Hydrogen can also be made by cracking :
C10H22 -> C7H14 + C3H6 + H2
Decane -> Alkene + Alkene + Hydrogen
Cracking is used to make :
- Alkenes
- Hydrogen
- Petrol from higher fractions
Addition Reaction :
Hydrogenation
Condition - 180 degree celsius, Nickel catalyst
Alkene + Hydrogen -> Alkane
Hydration
Condition - 300 degree celsius, Phosphoric Acid, 60 atmospheric pressure
Alkene + Water -> Alcohol
Test for an alkene
When a few drops of Bromine water are added to a tube of ethene gas, the colour changes from brown to colourless.
Ethene + Bromine -> Dibromoethane
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lol u started
i ws thinkin of starting it 2day
By the way i wil pm u de useful ntes n tricks i hav
!!!!
:P
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thanxs a good information
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i was gonna start mine 2mrw :(
i guess u go on with this :/ ill make another
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Organic Chemistry
Fuels :
- Coal
- Natural gas (Methane)
- Petroleum (Crude oil)
Fractional distillation:
N/A - Refinery gas (used as a fuel)
30 degree celsius - Gasoline (used as a fuel in cars)
110 degree celsius - Naphtha (used as make chemicals)
180 degree celsius - Kerosene / Paraffin (used as a fuel in jet engines)
260 degree celsius - Diesel oil / Gas oil (used as a fuel in diesel engines)
N/A - Fuel oil (used as a fuel for ships and for home heating systems)
N/A - Lubricating oil (used in waxes and polishes)
N/A - Bitumen (used as a fuel in jet engines)
Homologus series :
- Trend in physical properties
- Same general formula
- Same functional group
- Similar chemical properties
- Differs from its neighbouring member by CH2
Properties of Alkanes :
Saturated hydrocarbons
General formula : CnH(2n+2)
Increase in boiling point
Physical state at room temperature : Gas > Liquid > Solid
Combustion of alkanes :
Gives CO2 and water, incomplete combustion will give CO and water.
Subsitution reaction :
Condition - Bright light (Photochemical)
Alkanes react with chlorine to give a mixture of chloroalkanes. One hydrogen atom is subsituted by one chlorine atom.
Methane + Chlorine -> Chloromethane (CH3Cl) + HCl
Amazing stuff Darren
u summarized the whole chapter!
thanks a lot man
dude u forgot one more thing
in halogenation
u also need lead tetraethyl and a high temprature
UV/Bright light is the main answer though
thanks anyway dude :)
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i was gonna start mine 2mrw :(
i guess u go on with this :/ ill make another
Perhaps we should collaborate or something ... I am hopeless at drawing diagrams, would you be kind enough to provide illustrations on branched alkanes?
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Amazing stuff Darren
u summarized the whole chapter!
thanks a lot man
dude u forgot one more thing
in halogenation
u also need lead tetraethyl and a high temprature
UV/Bright light is the main answer though
thanks anyway dude :)
Not even close :D Still got alcohol, alkanoic acid and ester ... Not to mention addition and condensation polymerisation *sigh*
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Perhaps we should collaborate or something ... I am hopeless at drawing diagrams, would you be kind enough to provide illustrations on branched alkanes?
Do you mean something like this:
(http://www.hpwt.de/Chemie/Alkanee.gif)
http://www.hpwt.de/Chemie/Alkanee.gif (http://www.hpwt.de/Chemie/Alkanee.gif)
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Do you mean something like this:
(http://www.hpwt.de/Chemie/Alkanee.gif)
http://www.hpwt.de/Chemie/Alkanee.gif (http://www.hpwt.de/Chemie/Alkanee.gif)
Yea but when you ... well branch it, say for butane we can have ... methylpropane, if you catch my drift LOL.
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Yea but when you ... well branch it, say for butane we can have ... methylpropane, if you catch my drift LOL.
You want me to post them?
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Yea but when you ... well branch it, say for butane we can have ... methylpropane, if you catch my drift LOL.
Oh...you want isomers. OK here are isomers for butane:
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Here are isomers for pentane:
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Thanks :D
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Here are isomers for pentane:
how do you know what the isomers are named?
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how do you know what the isomers are named?
It's complicated. We shall use the isomers of butane as the example. The first one is easy, just butane. The second one:
a) You take the longest carbon cahin and name the compound after the number of carbon atoms in the longest chain. In this case, there are three carbon atoms in the longest chain. So it is named after propane.
b) You then look for the alkyl side chain. In this case it is a methyl group (CH3). So the compound is methylpropane.
c) You then have to number the alkyl group side chain by counting the numbers of the carbon atoms from one end of the carbon chain. You count from the end of the carbon chain that gives you the lowest number. In this case counting from the left/right, the alkyl group is on the second carbon atom. So the compound is 2-methylpropane.
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It's complicated. We shall use the isomers of butane as the example. The first one is easy, just butane. The second one:
a) You take the longest carbon cahin and name the compound after the number of carbon atoms in the longest chain. In this case, there are three carbon atoms in the longest chain. So it is named after propane.
b) You then look for the alkyl side chain. In this case it is a methyl group (CH3). So the compound is methylpropane.
c) You then have to number the alkyl group side chain by counting the numbers of the carbon atoms from one end of the carbon chain. You count from the end of the carbon chain that gives you the lowest number. In this case counting from the left/right, the alkyl group is on the second carbon atom. So the compound is 2-methylpropane.
THANK YOU ! :D
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Properties of Alcohols :
-OH (Hydroxyl) functional group
General formula : Cn H(2n+1) OH
Ethanol can be manufactured :
- Hydration of ethene
- Fermentation
Ethanol burns with a clean flame. It is used for camping stoves or as a fuel for cars.
The complete combustion of etanol produces carbon dioxide and water.
Ethanol is also used as a fuel, as a solvent in perfume, alcoholic drinks and making esters.
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Properties of Organic Acids :
-COOH functional group
General formula : Cn H(2n+1) COOH
Ethanol is oxidised to ethanoic acid.
Ethanol + O2 (from the air) -> Ethanoic acid + Water
When ethanol is heated with acidified K2Cr2O7 (Potassium dichromate), ethanoic acid is formed.
Ethanol + O2 (from the oxidising agent) -> Ethanoic acid + Water
Organic acids are weak acids, they are partially ionised in aqueous solution. They all have the typical acid properties.
Metal + Acid -> Salt + Hydrogen
Magnesium + Ethanoic acid -> Magnesium ethnoate [(Ch3COO)2Mg] + Hydrogen
Base + Acid -> Salt + Water
Magnesium + Ethanoic acid -> Magnesium ethnoate [(Ch3COO)2Mg] + Water
Carbonate + Acid -> Salt + Carbon Dioxide + Water
Sodium Carbonate + Ethanoic acid -> Sodium ethnoate [(Ch3COO)Na] + Carbon Dioxide + Water
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Properties of Esters :
Ethanoic acid + Ethanol -> Ethyl Ethnoate + QWater
Condition :
- Heat
- Concenterated sulphuric acid as catalyst
Esters are used in food flavourings.
When writing the name of an ester, the group from the alcohol comes before the part from the part from the acid. For example if methanol is reacted with propanoic acid, we will get methyl propanoate.
When drawing an ester, the acid part is on the left and the alcohol part is on the right.
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Properties of Esters :
Ethanoic acid + Ethanol -> Ethyl Ethnoate + QWater
Condition :
- Heat
- Concenterated sulphuric acid as catalyst
Esters are used in food flavourings.
When writing the name of an ester, the group from the alcohol comes before the part from the part from the acid. For example if methanol is reacted with propanoic acid, we will get methyl propanoate.
When drawing an ester, the acid part is on the left and the alcohol part is on the right.
I've included pictures so it's more obvious for people to see! :P
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I've included pictures so it's more obvious for people to see! :P
Thanks Ivo.
Kimo : I am planning to do Air and water, Carbonates and Sulphates, perhaps you might be willing to help out with the remainder of the topics ???
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WOW! Thank you guys Soooooooo MUCH!! These are so helpful!
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Thanks
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good job dude
amazing notes
keep going
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did you get this from the study guide?... anyway thanks
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did you get this from the study guide?... anyway thanks
Yeah, but I filtered out the information that are not essential.
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Yeah, but I filtered out the information that are not essential.
i wanna help temme which topic do u want me 2 do :)
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i wanna help temme which topic do u want me 2 do :)
I shall be responsible for the remainder of Organic Chemistry, Air and Water, Carbonates and Sulphates.
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Yeah, but I filtered out the information that are not essential.
By the way, which study guide is this from, may I ask?
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I shall be responsible for the remainder of Organic Chemistry, Air and Water, Carbonates and Sulphates.
hey tell me de topic dat i can do
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hey tell me de topic dat i can do
The remainder of the topics ...
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Download this file............
then pls anss my q
can somebody list the imp.reactions that would probably come on 7th plssssssssssssss
or give the link where it is stated......
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HEy guys ,i'm really in trouble, the problem is that my chemistry guide(bob berry) is missing an important page(Pg 33 to 34) ,about excess reagents and coincidentally ,i always mess up that question and lose marks,so could someone scan the page off the guide and post it,or even a picture would do, i'm sure you''ll wil understand ,thanks! :) :D :)
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Download this file............
then pls anss my q
can somebody list the imp.reactions that would probably come on 7th plssssssssssssss
or give the link where it is stated......
Gaurav..
so u really cant ask for an easy way out...because there is a possibility of anything arising
but I feel u should study important processes such as extraction of metals especially iron,aluminium,zinc and copper
then also the haber's process and contact process.
Study chromatography thoroughly as it could come in ppr 3...
Oh yeah also study the production of nitric acid..hasnt really come before so it could now
also yeah study the basic reactions (acid+base,acid+metal etc)
Electrolysis too
good luck
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Gaurav..
so u really cant ask for an easy way out...because there is a possibility of anything arising
but I feel u should study important processes such as extraction of metals especially iron,aluminium,zinc and copper
then also the haber's process and contact process.
Study chromatography thoroughly as it could come in ppr 3...
Oh yeah also study the production of nitric acid..hasnt really come before so it could now
also yeah study the basic reactions (acid+base,acid+metal etc)
Electrolysis too
good luck
Thx but will still be looking for some input...........
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Gaurav..
so u really cant ask for an easy way out...because there is a possibility of anything arising
but I feel u should study important processes such as extraction of metals especially iron,aluminium,zinc and copper
then also the haber's process and contact process.
Study chromatography thoroughly as it could come in ppr 3...
Oh yeah also study the production of nitric acid..hasnt really come before so it could now
also yeah study the basic reactions (acid+base,acid+metal etc)
Electrolysis too
good luck
Extraction of copper is omitted.
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Can anyone help me with moles? i never got their head or toe........tym is almost up n i kno as much moles as i did three years ago when i did them them fr the first tym! HELP! any tricks....tips......anYthing! :'( :'( :'(
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Can anyone help me with moles? i never got their head or toe........tym is almost up n i kno as much moles as i did three years ago when i did them them fr the first tym! HELP! any tricks....tips......anYthing! :'( :'( :'(
It's hard to 'teach' you moles. My advice is go through past paper questions, and then you'll find it is well easy!
I've written very thorough explanations for some questions and doubts people have asked. Here they are:
s02, Q5) c) and d):
The equation you need to use is:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Note to convert cm3 to dm3, divide quantity by 1000 (e.g. 20cm3/1000=0.02dm3)
This is the proper theory and equation behind my calculations below.
Here are the answers for 5) c) as requested:
i) Moles of C4H6: 0.02/24=0.000833
From equation, we know 2 moles of C4H6 reacts with 11 moles of O2
Therefore, moles of O2: 0.000833*5.5=0.00458
Therefore, volume of O2: 4.58*24*1000=110cm3
ii) From equation, we know 2 moles of C4H6 produces 8 moles of CO2
Therefore, moles of CO2: 0.000833*4=0.00333
Therefore, volume of CO2: 0.00333*24*1000=80cm3
iii) From equation, we know 2 moles of C4H6 produces 6 moles of H2O
Therefore, moles of H2O: 0.000833*3=0.0025
Therefore, volume of H2O: 0.0025*24*1000=60
Therefore, total volume of gases is simply volume of CO2 + volume of H2O:
80+60=140cm3
Alternatively, 8+6=14, so 2 moles of C4H6 produces 14 moles of products
Therefore, moles of products: 0.000833*7=0.00583
Therefore, volume of products: 0.00583*24*1000=140cm3
For part d), you use this formula:
Mass
Moles = ------
Mr
d) From the above equation, 1 mole of butyne forms 3 moles of water
Number of moles of butyne reacted: 9/54=0.167
Number of moles of water formed: 0.167*3=0.5
Mass of water formed: 0.5*(2+16)=9g
I hope this has helped. :D
s08, Q7) b)
OK, hopefully this clears your doubt.
This time, you'll need to also apply this formula:
Concentration (mol/dm3) = Moles / Volume (dm3)
So:
i) Number of moles of NaOH used = 2.24*0.025 = 0.056 mols
ii) Maximum number of moles of Na2SO4.10H2O that could be formed = From the equation given, you can see 2 moles of NaOH gives 1 mole of Na2SO4.10H2O. So it is simply: 0.056/2 = 0.028 mols
iii) Mass of one mole of Na2SO4.10H2O = 322g
iv) Maximum yield of sodium sulphate-10-water = 0.028*322 = 9.02g
v) Percentage yield = (3.86/9.02)*100 = 42.8%
If you don't understand any of this, I'll be happy to explain ;)
w08, Q7) a)
The equation you need to use is:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Note to convert cm3 to dm3, divide quantity by 1000 (e.g. 20cm3/1000=0.02dm3)
This is the proper theory and equation behind my calculations below.
Here are the answers for 5) c) as requested:
i) Moles of C4H6: 0.02/24=0.000833
From equation, we know 2 moles of C4H6 reacts with 11 moles of O2
Therefore, moles of O2: 0.000833*5.5=0.00458
Therefore, volume of O2: 4.58*24*1000=110cm3
ii) From equation, we know 2 moles of C4H6 produces 8 moles of CO2
Therefore, moles of CO2: 0.000833*4=0.00333
Therefore, volume of CO2: 0.00333*24*1000=80cm3
iii) From equation, we know 2 moles of C4H6 produces 6 moles of H2O
Therefore, moles of H2O: 0.000833*3=0.0025
Therefore, volume of H2O: 0.0025*24*1000=60
Therefore, total volume of gases is simply volume of CO2 + volume of H2O:
80+60=140cm3
Alternatively, 8+6=14, so 2 moles of C4H6 produces 14 moles of products
Therefore, moles of products: 0.000833*7=0.00583
Therefore, volume of products: 0.00583*24*1000=140cm3
For part d), you use this formula:
Mass
Moles = ------
Mr
d) From the above equation, 1 mole of butyne forms 3 moles of water
Number of moles of butyne reacted: 9/54=0.167
Number of moles of water formed: 0.167*3=0.5
Mass of water formed: 0.5*(2+16)=9g
I hope this has helped. :D
s04, Q7) b):
7) b) i) Moles of Mg = 3/24 = 0.125
Moles of CH3COOH = 12/60 = 0.200
Using ratios given in the equation, to compare, divide 0.2/2 = 0.100 moles of CH3COOH.
Therefore, magnesium is in excess.
ii) The one not in excess: ie. 0.1
iii) 0.1*24 =2.4dm3
Got it?
I hope that's enough questions for you to follow! ;P
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i have a question.... w06 q8 c(iii)
how do i deduce the formula? i need to know that to ans the question
ms says the test is bromine water and the result for the first one is brown to colourless this means that it is an alkene right? bt hw do i knw that the first one is alkene from the fromula given?
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i have a question.... w06 q8 c(iii)
how do i deduce the formula? i need to know that to ans the question
ms says the test is bromine water and the result for the first one is brown to colourless this means that it is an alkene right? bt hw do i knw that the first one is alkene from the fromula given?
If its an alkene it will have the general formula Cn H2n where n is the number of carbon atoms
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If its an alkene it will have the general formula Cn H2n where n is the number of carbon atoms
um can you please check the question... do i count all the carbon atoms or just the ones on the first line?
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um can you please check the question... do i count all the carbon atoms or just the ones on the first line?
Hang on. :)
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um can you please check the question... do i count all the carbon atoms or just the ones on the first line?
C17H33 has two fewer hydrogen atoms compared to C17H35, we can deduce that C17H33 is an alkene straightaway ...
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C17H33 has two fewer hydrogen atoms compared to C17H35, we can deduce that C17H33 is an alkene straightaway ...
How does that prove anything ?
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C17H33 has two fewer hydrogen atoms compared to C17H35, we can deduce that C17H33 is an alkene straightaway ...
how does that prove its an alkene? isnt it supposed to be C17H34 for it to be an alkene?
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Here :
q8 c (iii)
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umm why are you posting the question paper?
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umm why are you posting the question paper?
Calling in backup ;)
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How does that prove anything ?
It was merely a guess, I haven't a clue about that question as well when I was doing the PP, I wrote that in the script and it turns out to be correct ...
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ahh i see :D
ill be here... waiting for the answer... :)
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One is saturated, the other is not.
Use bromine water test.
with fat1 it will decolorise
with fat 2 no change
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One is saturated, the other is not.
Use bromine water test.
with fat1 it will decolorise
with fat 2 no change
HOW do you determine which one will decolorise bromine water ? Obviously it will be one with C=C bonds, but HOW do you determine which one it is ?
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the one with less no of hydrogens is unsaturated...obv much
So in this case it's fat 1
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Hiiiii :D
i've got major problems with drawing monomers and polymers D:
HELP PLEASEEE, THANKS ;D ;D ;D
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check the files attached :)
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check the files attached :)
haha, okayyy thank you :) :) then whut about the silver particles? do we have to add them on the monomer/polymer?
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Nope. Polymer=polypropene...clearly mentioned... ;)
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Nope. Polymer=polypropene...clearly mentioned... ;)
okayyy :D thanks.
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haha, okayyy thank you :) :) then whut about the silver particles? do we have to add them on the monomer/polymer?
http://img85.imageshack.us/img85/5738/monomerandpolymer.png
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May june 04 q 4 b 2 why until 8 mm it .. isnt there a range ?
Plus b 3 I have no idea what is going on i need help .. could any1 help?
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Hey you guys! I posted before many chemistry links which might be helpful and I'll post them again :
https://studentforums.biz/index.php/topic,3803.0.html
https://studentforums.biz/index.php/topic,1615.0.html
http://www.mediafire.com/download.php?wyymt3nntwj
http://www.docbrown.info/page10/page10.htm
http://www.knockhardy.org.uk/assets/MCANE.HTM
http://www.knockhardy.org.uk/assets/MCENE.HTM
https://studentforums.biz/index.php/topic,4304.0.html
http://www.gcsescience.com/index.html
https://studentforums.biz/index.php/topic,4425.45.html
Best of luck!
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Check this thread also. I just posted the notes today :
https://studentforums.biz/index.php/topic,8769.0.html
If like, +rep me please :P and pray for my a-levels. =] <3
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Thnkx soooo much! i hope da qs is ezy...... ;D
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Thnkx soooo much! i hope da qs is ezy...... ;D
me 2
nyway guys
is there any way u can learn the reactivity series easily
im havin trouble with that
By the way the reactivity series ;)
Potassium K
Sodium Na
Lithium Li
Calcium Ca
Magnesium Mg
Aluminium Al
Carbon C
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Silver Ag
Gold Au
Platinum Pt
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Playing soccer less can make all zappy, considering I totally love Hanna because she’s gorgeous (and) pretty
Potassium K
Sodium Na
Lithium Li
Calcium Ca
Magnesium Mg
Aluminium Al
Carbon C
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Silver Ag
Gold Au
Platinum Pt
lol i modified a bit original was::“Playing soccer can make all zappy, I love Hanna because she’s gorgeous”
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Playing soccer less can make all zappy, considering I totally love Hanna because she’s gorgeous (and) pretty
Potassium K
Sodium Na
Lithium Li
Calcium Ca
Magnesium Mg
Aluminium Al
Carbon C
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Silver Ag
Gold Au
Platinum Pt
lol i modified a bit original was::“Playing soccer can make all zappy, I love Hanna because she’s gorgeous”
thx
lol
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u skipped carbon tho...
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u skipped carbon tho...
my bad, I put "considering" unnecessarily.. new revised version.. :P
Playing soccer less can make all comrades zappy, I totally love Hanna because she’s gorgeous (and) pretty ;D
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my bad, I put "considering" unnecessarily.. new revised version.. :P
Playing soccer less can make all comrades zappy, I totally love Hanna because she’s gorgeous (and) pretty ;D
dude
u da best
thx
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dude
u da best
thx
By the way the source is from this guide ::) ..So I wont take full credit ;) yes but I would take the credit of modifying it though :P
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my bad, I put "considering" unnecessarily.. new revised version.. :P
Playing soccer less can make all comrades zappy, I totally love Hanna because she’s gorgeous (and) pretty ;D
hmm mm hanna
:P
me likes it
lol
if u lsn myn u will rofl!!1
4get it
Thanks vin
!!
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hmm mm hanna
:P
me likes it
lol
if u lsn myn u will rofl!!1
4get it
Thanks vin
!!
nahi yaar
laga do
the more the merrier
shayed assan ho
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Thanks 4 de modified 1 because i knw de b4 1 u posted
!!
:)
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Thanx VIN1094. :) Thanks for the link to FAWESOME GUIDE & the Mnemonic too. :)
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its easier if you memorized knaca mgal czn fe pb hcu agau if youre arab youll see what i mean
and now my question
how do you know wich is the limiting reagent if the mole ratio is NOT 1:1 :) :)
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Popular Scientists Can Make A Zoo In The Low Humidity Countryside, More Satisfactory...Goodbye
Potassium K
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Mercury
Silver Ag
Gold Au
By the way I forgot who posted this ???
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A@di. ;)
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how do you know wich is the limiting reagent if the mole ratio is NOT 1:1 :) :)
Post a past paper question, it'll be easier to explain =]
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Popular Scientists Can Make A Zoo In The Low Humidity Countryside, More Satisfactory...Goodbye
Potassium K
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Mercury
Silver Ag
Gold Au
By the way I forgot who posted this ???
Mentioning reactivity series we are also required to know that metals above Zinc cannot be extracted by heating with Carbon, metals below Hydrogen does not react with acid to form salt and hydrogen, Copper does not react with steam and cold water, whereas Magnesium, Zinc and Iron only reacts with steam.
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Addition polymerisation - Only produces the polymer
Condensation polymerisation - Produces water and polymer
Uses of polymers :
Nylon and terylene - make clothes
Nylon - rope making
PVC - electrical insulator and pipes
Poly(ethene) - bowls, buckes and plastic bags
Plastic and pollution :
- Source of visual pollution
- Burning produces toxic gas
Nylon and proteins :
C=O-OH and NH2 monomers
Proteins has many monomers as it is a biological polyamide, whereas synthetic polyamide, such as nylon, only contains the aforementioned monomers.
When they are joined together, an amide linkage C=O-NH is formed, water is eliminated in forming this linkage.
Amino acids -> Water + Protein (Condensation polymerisation)
Water + Protein -> Amino acids (Hydrolysis, boil with hydrochloric acid)
Polyesters :
C=O-OH and OH monomers
When they are joined together, an ester linkage C=O-O is formed, water is eliminated in forming this linkage.
Fats :
Animal fats and vegetable oils are esters.
Fat (Glyceryl sterate) + Sodium hydroxide -> Sodium salt of long-chain organic acid (Sodium sterate) + Glycerol
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Carbonhydrates :
Contains only Carbon, Hydrogen and Water.
The ratio of Hydrogen to Oxygen atoms is in 2:1 ratio.
Glucose - C6H12O6
Starch - (C6H10O5)n
Two OH monomers were joined to form Starch :
-O-[]-O-[]-O-[]-
Glucose -> Starch + Water (Condensation polymerisation)
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Acid hydrolysis of complex hydrocarbons :
Heated with dilute HCl, the acid is a catalyst in this reaction.
Starch + Water -> Glucose
The reaction can be catalysed by enzymes, but the sugar produces would be different.
Fermentation :
Glucose -> Ethanol + Carbon Dioxide
Catalysed by enzymes from yeast.
The reaction is an anaerobic respiration of yeast cells, oxygen in air would oxidise ethanol to carbon dioxide.
35 degree celsius - optimal temperature. Too high - enzymens gets denatured. Too low - rate would be too slow to be economical.
Fermentation ceases when the concentration of ethanol reaches 14%, this is because ethanol is poisonous to yeast, and at this concentration yeast dies. All the glucose has been used up.
C6H12O6 -> 2C2H5OH + 2CO2
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its easier if you memorized knaca mgal czn fe pb hcu agau if youre arab youll see what i mean
and now my question
how do you know wich is the limiting reagent if the mole ratio is NOT 1:1 :) :)
ya i heard that one before, i heard a chemistry teacher saying,
knaca thin and age of lead...
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Acid hydrolysis of complex hydrocarbons :
Heated with dilute HCl, the acid is a catalyst in this reaction.
Starch + Water -> Glucose
The reaction can be catalysed by enzymes, but the sugar produces would be different.
Fermentation :
Glucose -> Ethanol + Carbon Dioxide
Catalysed by enzymes from yeast.
The reaction is an anaerobic respiration of yeast cells, oxygen in air would oxidise ethanol to carbon dioxide.
35 degree celsius - optimal temperature. Too high - enzymens gets denatured. Too low - rate would be too slow to be economical.
Fermentation ceases when the concentration of ethanol reaches 14%, this is because ethanol is poisonous to yeast, and at this concentration yeast dies. All the glucose has been used up.
C6H12O6 -> 2C2H5OH + 2CO2
Oxygen will oxidise ethanol 2 ethanoic acid, da atmospheric oxygen is not enough to oxidise it to CO2....! da rest r impressive, great work!!!
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GOOD LUCK TO EVERYONE FOR TOMORROW
GOOD LUCK
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Could someone please explain may june 09 paper 32 q 5 b ???
I know it's for instance K3PO4 or T3 PO4.. but the other 2 marks not quite so any help??
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Oxygen will oxidise ethanol 2 ethanoic acid, da atmospheric oxygen is not enough to oxidise it to CO2....! da rest r impressive, great work!!!
Not according to the endorsed revision guide :D
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Could someone please answer me i already feel depressed :S ??
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why de rate of rustin is increased in presence of acid and salt water
can sum on eplz answer
thanz in advance ;D
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why de rate of rustin is increased in presence of acid and salt water
can sum on eplz answer
thanz in advance ;D
BECAUS they contain IONS which can transfer electrons which speed up rusting or oxidation!
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BECAUS they contain IONS which can transfer electrons which speed up rusting or oxidation!
i.e they are electrolytes.
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Hey, can any1 please explain the contents of section 6.2 in the syllabus?! I really get nothing from it! ??? ???
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Hey, can any1 please explain the contents of section 6.2 in the syllabus?! I really get nothing from it! ??? ???
Yea sure, You just have to know that hydrogen is a better fuel because the product of its combustion is water which isnt a pollutant advantages are that it will conserve natural resources and doesn't cause pollution. You just have to know the name Uranium-235 is used as a fuel cell. The electrode is a big topic. For the hydrogen one in supplement they have already said it. Anything I missed?
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Yea sure, You just have to know that hydrogen is a better fuel because the product of its combustion is water which isnt a pollutant advantages are that it will conserve natural resources and doesn't cause pollution. You just have to know the name Uranium-235 is used as a fuel cell. The electrode is a big topic. For the hydrogen one in supplement they have already said it. Anything I missed?
Thank You so much, but what about the prdoduction of energy from a simple cell thingy?
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6.2 Production of energy
-Describe the production of heat energy by burning fuels
Buring fossil fuels, such as coal, natural gas and petroleum (crude oil) produces heat energy.
-Describe hydrogen as a fuel
Pros : Does not produce oxides of nitrogen when buring, the most energy rich fuel, only product of combustion is water.
Cons : Expensive and difficult to store
-Describe radioactive isotopes, such as 235 U, as a source of energy
Heat energy and then electrical energy is produced from nuclear reactors.
-Describe the production of electrical energy from simple cells, i.e. two electrodes in an electrolyte.
Electrons flow from the negative electrode to the positive electrode through the external circuit in an electrolytic fuel cell (also electrolysis).
Zinc electrode, Copper electrode and dilute Sulphuric acid electrolyte are used as an example here.
Since Zinc is more reactive than copper, it is the negative electrode, oxidation takes place (Zn -> Zn2+ + 2e-). The elctrons flows through the external circuit to the Copper electrode, the positive ion from the electrolyte (i.e. Hydrogen ions) gets reduced here.
The greater the difference between the reactivity of the two metal electrodes used, the greater the voltage of the circuit would be.
-Describe the use of hydrogen as a potential fuel reacting with oxygen to generate electricity in a fuel cell
Hydrogen is supplied to the negative electrode : H2 -> 2H+ + 2e-
The electrons flows through the external circuit to the positive electrode.
Oxygen is supplied to the positive electrode : O2 + 2H2O + 4e- -> 4OH-
The ions react to produce water : H+ + OH- -> H2O
The overall reaction is : 2H2 + O2 -> 2H2O
When hydrogen reacts with oxygenm to form water in a fuel cell, electrical energy is procued.
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Thank You so much, but what about the prdoduction of energy from a simple cell thingy?
No problem :), There are two things. A cell and an electrolyte.
A cell- Chemical energy is converted to electrical energy(basically its a battery)
the reaction is exothermic because by chemical energy electrical energy is produced
The flow of es is from more reactive metal to least reactive. At the more reactive electrode oxidation takes place and the metal atoms become ions. The less reactive electrode is reduction. So bubbles of a gas which is hydrogen. always bubbles produced at less reactive.
Electrolyte- Electrical energy is used to bring a chemical change. So basically this reaction is endothermic because electrical energy is needed to bring a change in the electrolyte. This part is in electrolysis.
I hope I helped :)
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By the way just a little bit more about U-235
Produces energy without using oxygen. But all other fuels need oxygen.
Uses are in industry which are:
1) Power generators
2) Treatment of cancer
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6.2 Production of energy
-Describe the production of heat energy by burning fuels
Buring fossil fuels, such as coal, natural gas and petroleum (crude oil) produces heat energy.
-Describe hydrogen as a fuel
Pros : Does not produce oxides of nitrogen when buring, the most energy rich fuel, only product of combustion is water.
Cons : Expensive and difficult to store
-Describe radioactive isotopes, such as 235 U, as a source of energy
Heat energy and then electrical energy is produced from nuclear reactors.
-Describe the production of electrical energy from simple cells, i.e. two electrodes in an electrolyte.
Electrons flow from the negative electrode to the positive electrode through the external circuit in an electrolytic fuel cell (also electrolysis).
Zinc electrode, Copper electrode and dilute Sulphuric acid electrolyte are used as an example here.
Since Zinc is more reactive than copper, it is the negative electrode, oxidation takes place (Zn -> Zn2+ + 2e-). The elctrons flows through the external circuit to the Copper electrode, the positive ion from the electrolyte (i.e. Hydrogen ions) gets reduced here.
The greater the difference between the reactivity of the two metal electrodes used, the greater the voltage of the circuit would be.
-Describe the use of hydrogen as a potential fuel reacting with oxygen to generate electricity in a fuel cell
Hydrogen is supplied to the negative electrode : H2 -> 2H+ + 2e-
The electrons flows through the external circuit to the positive electrode.
Oxygen is supplied to the positive electrode : O2 + 2H2O + 4e- -> 4OH-
The ions react to produce water : H+ + OH- -> H2O
The overall reaction is : 2H2 + O2 -> 2H2O
When hydrogen reacts with oxygenm to form water in a fuel cell, electrical energy is procued.
Yur Amazing Dude! Thank You :D
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No problem :), There are two things. A cell and an electrolyte.
A cell- Chemical energy is converted to electrical energy(basically its a battery)
the reaction is exothermic because by chemical energy electrical energy is produced
The flow of es is from more reactive metal to least reactive. At the more reactive electrode oxidation takes place and the metal atoms become ions. The less reactive electrode is reduction. So bubbles of a gas which is hydrogen. always bubbles produced at less reactive.
Electrolyte- Electrical energy is used to bring a chemical change. So basically this reaction is endothermic because electrical energy is needed to bring a change in the electrolyte. This part is in electrolysis.
I hope I helped :)
Thank You again x], nd yea, yu dd help :D
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hello .. hope everyones doing well
can some1 please tell me wht i need 2 kno for thermal decomposition for 2mrrw
thanks in advance :D
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hello .. hope everyones doing well
can some1 please tell me wht i need 2 kno for thermal decomposition for 2mrrw
thanks in advance :D
Metal Nitrate:
(upon heating)
Group 1: Metal Nitrate > Metal Nitrite + Oxygen
Group 2 & Others : Metal Nitrate > Metal Oxide + Nitrogen Dioxide + Oxygen
Metal Hydroxide :
(upon heating)
Group 1 : No Decomposition
Group2 & Others : Metal Hydroxide > Metal Oxide + Water
Metal Carbonate:
(upon heating)
Group 1: No Decomposition
Group 2 & Others : Metal Carbonate > Metal Oxide + CarbonDioxide
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Best of luck to all attempting the Chemistry Paper 3 tomorrow, hopefully it'll be good, and we will all score good marks!
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6.2 Production of energy
-Describe the production of heat energy by burning fuels
Buring fossil fuels, such as coal, natural gas and petroleum (crude oil) produces heat energy.
-Describe hydrogen as a fuel
Pros : Does not produce oxides of nitrogen when buring, the most energy rich fuel, only product of combustion is water.
Cons : Expensive and difficult to store
-Describe radioactive isotopes, such as 235 U, as a source of energy
Heat energy and then electrical energy is produced from nuclear reactors.
-Describe the production of electrical energy from simple cells, i.e. two electrodes in an electrolyte.
Electrons flow from the negative electrode to the positive electrode through the external circuit in an electrolytic fuel cell (also electrolysis).
Zinc electrode, Copper electrode and dilute Sulphuric acid electrolyte are used as an example here.
Since Zinc is more reactive than copper, it is the negative electrode, oxidation takes place (Zn -> Zn2+ + 2e-). The electrons flow through the external circuit to the Copper electrode, the positive ion from the electrolyte (i.e. Hydrogen ions) gets reduced here.
The greater the difference between the reactivity of the two metal electrodes used, the greater the voltage of the circuit would be.
-Describe the use of hydrogen as a potential fuel reacting with oxygen to generate electricity in a fuel cell
Hydrogen is supplied to the negative electrode : H2 -> 2H+ + 2e-
The electrons flows through the external circuit to the positive electrode.
Oxygen is supplied to the positive electrode : O2 + 2H2O + 4e- -> 4OH-
The ions react to produce water : H+ + OH- -> H2O
The overall reaction is : 2H2 + O2 -> 2H2O
When hydrogen reacts with oxygenm to form water in a fuel cell, electrical energy is procued.
hey isnt zinc placed as the ANODE not cathode in the cell? or is this electrolysis? :S aakh im so confused. cuz there was a qs in 08 or 07 i dno and it was like gsacrificial protection using tin as the anode and the steel as the cathode. the tin lost electrons, giving them to steel to prevent the steel form oxidising.
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hey isnt zinc placed as the ANODE not cathode in the cell? or is this electrolysis? :S aakh im so confused. cuz there was a qs in 08 or 07 i dno and it was like gsacrificial protection using tin as the anode and the steel as the cathode. the tin lost electrons, giving them to steel to prevent the steel form oxidising.
Um, does this help?:: https://studentforums.biz/index.php/topic,1411.msg254665.html#msg254665
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Um, does this help?:: https://studentforums.biz/index.php/topic,1411.msg254665.html#msg254665
yes it does thank you! so the "negative pole" is actually the anode and vice versa?
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yes it does thank you! so the "negative pole" is actually the anode and vice versa?
See, in a cell there is nothing called anode or cathode. Like I mentioned, just -ve and +ve poles. If you see you regular AA/AAA batteries have + and -, it is the same here.
An anode forms when an electrode is given the +ve charge, and -ve charge for cathode.
Here The +ve and -ve charges are produced.
Always in a cell the more reactive metal is the -ve terminal as it is the source of e-.
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See, in a cell there is nothing called anode or cathode. Like I mentioned, just -ve and +ve poles. If you see you regular AA/AAA batteries have + and -, it is the same here.
An anode forms when an electrode is given the +ve charge, and -ve charge for cathode.
Here The +ve and -ve charges are produced.
Always in a cell the more reactive metal is the -ve terminal as it is the source of e-.
thank you but see here qs 5 b http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_3.pdf[url]] (http://[/url)http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_3.pdfhttp://
it specifically says anode and cathode :/ is it a cell or electrolysis?
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thank you but see here qs 5 b http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_3.pdf[url=http://]]] (http://[/url)http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_3.pdfhttp://
it specifically says anode and cathode :/ is it a cell or electrolysis?
Um, electrolysis is 5 b)i ans ii. This is something CIE wants to confuse people, you might have never learned about it but you should use your concepts of oxidation and reduction. Something to be oxidised needs to loose electrons, (rusting is a type of oxidation), if you see there is a power supply which provides constant supply of e- which doesn't allow it to rust.
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Metal Nitrate:
(upon heating)
Group 1: Metal Nitrate > Metal Nitrite + Oxygen
Group 2 & Others : Metal Nitrate > Metal Oxide + Nitrogen Dioxide + Oxygen
Metal Hydroxide :
(upon heating)
Group 1 : No Decomposition
Group2 & Others : Metal Hydroxide > Metal Oxide + Water
Metal Carbonate:
(upon heating)
Group 1: No Decomposition
Group 2 & Others : Metal Carbonate > Metal Oxide + CarbonDioxide
thank u soo much very helpful.. !!!
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Leaving for Chemistry Paper 3 now. Very nervous! My paper starts after 1 and a half hours...
Wish me Luck, guys!
Pray for me, and I shall pray for you! :D
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going for d xam in an hour.....
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Um, electrolysis is 5 b)i ans ii. This is something CIE wants to confuse people, you might have never learned about it but you should use your concepts of oxidation and reduction. Something to be oxidised needs to loose electrons, (rusting is a type of oxidation), if you see there is a power supply which provides constant supply of e- which doesn't allow it to rust.
thanks :)
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yo amigos ...........i hope y'all roast the paper today ,if u kno what i mean :P
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yo amigos ...........i hope y'all roast the paper today ,if u kno what i mean :P
You evil meanie -v- Jokes ... Well I had my exam earlier this afternoon, a high A* is guaranteed, sadly no chance of Top in the World nor Brilliance in Hong Kong due to two careless mistakes that I would never concede in unit tests and internal mocks D:
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You evil meanie -v- Jokes ... Well I had my exam earlier this afternoon, a high A* is guaranteed, sadly no chance of Top in the World nor Brilliance in Hong Kong due to two careless mistakes that I would never concede in unit tests and internal mocks D:
lol.....well atleast an A* is guaranteed mate ;)
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lol.....well atleast an A* is guaranteed mate ;)
This can be best described as a stinging bitterness, checked thrice with the lab dude and chemistry teacher at school, am very confident that I have gotten every single questions in papers 1 and 5 correctly ... I probably have lost three marks at max in Paper 3, but since my ultimate aspiration is Top in the World, it is a major setback nonetheless ...
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This can be best described as a stinging bitterness, checked thrice with the lab dude and chemistry teacher at school, am very confident that I have gotten every single questions in papers 1 and 5 correctly ... I probably have lost three marks at max in Paper 3, but since my ultimate aspiration is Top in the World, it is a major setback nonetheless ...
The past is quite simply; the past. No matter how hard you try the clock cannot be turned backed.
Relish your A* and be ready to put a wide smile on your parent's face. ;)
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yo amigos ...........i hope y'all roast the paper today ,if u kno what i mean :P
yup we roasted, heated and burned in air,
and obtained it pure. :D
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yup we roasted, heated and burned in air,
and obtained it pure. :D
You have forgotten to wash it with water prior to roasting in order to remove traces of the solution in percipitation :P
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yup we roasted, heated and burned in air,
and obtained it pure. :D
hahahaha ..LMAO ..lool
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As all IGCSE chemistry exams are over, this topic will be locked.
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As all IGCSE chemistry exams are over, this topic will be locked.
Nooo!!!! Why are you locking all topics?!???!?!
There is still OCT/NOV session coming up and people might want to post here!
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Nooo!!!! Why are you locking all topics?!???!?!
There is still OCT/NOV session coming up and people might want to post here!
*SMACKS HEAD* OH damn I forgot, I'll unlock this. :-X
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*SMACKS HEAD* OH damn I forgot, I'll unlock this. :-X
LOL I knew you forgot.
Its alright, just unlock the rest also.
You want to be a moderator on this board between? Shall I add your name here?
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LOL I knew you forgot.
Its alright, just unlock the rest also.
You want to be a moderator on this board between? Shall I add your name here?
OKAY !!!! ;D
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You have forgotten to wash it with water prior to roasting in order to remove traces of the solution in percipitation :P
haha lol :D
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OKAY !!!! ;D
oh oh strict guy watching,
:Pjk Ari :P