IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: cockyxrocker on April 25, 2009, 01:44:48 pm
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A reaction occured which can be represented by the following equation
Steam + magnesium ---> magnesium oxide + gas v
1.What was the appearance of the magnesium
(i)before the experiment?
(ii)after the experiment?
(iii)Suggest an identity for gas v
(iv)Suggest a test for gas v
(v)Suggest why the tube containing the magnesium ofen cracks on cooling.
I only need help with the last part...dont know how to exactly answer it.
Thanks in advance ^^
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look the reaction is highly exothermic .. so this heats the test tube a lot and the test tube expands ( solids usually expand on heating)
when u cool it suddenly (like by putting it in cold water or even normal tap water) it contract back suddenly .. so it cracks ..
especially if a part of the tube is cooled before the other
hope this helps ;)
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Thanks :D
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hey
Can anyone tell me which topics should i prepare for my Chemistry paper6 ??? i mean the name of the topics. And should i prepare the whole book for the paper 6 or just few topics will be enough???
Plzzz help me thanks.
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paper 6 chemistry is pretty easy.Pay attention to the laboratory equipments and such things.Ofcourse you know how tomeasure things and draw graphs..In addition to the acid&bases table and the experiments plans which come the last page of the paper.. Solve as much past papers as you can types of questions are always the same..
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Thanks :)
By the way can u tell me which chemistry book are you using?
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actually I dont use my book mainly..i use my teacher's notes..or you can say book! But anyway i'll post the book's name by tomorrow.
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oya in which paper does the above question appear in? its so un-IGCSE-ish rite? i mean about the cracking of the glass.. isn't that like physics?
just asking! oya can anyone post a good link or something wer u can get a list of eperiments that u need to now? thanks!
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I think it is physicssy too.
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Q:In Sweden, caesium-137 built up in small plants called lichen. These plants were eaten by reindeers and gave rise to radioactive meat.
(i) If radioactive caesium was reacted with the chlorine, would you expect the caesium chloride produced to be radioactive? Explain your answer.
I dont knw how to exactly answer this question ??? Can anyone tell me how to answer this question ???
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Please inform me with your Chemistry subject code.
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This is the question from IGCSE past papers... the year is 1992... thats why i dont knw the answer :(
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Yes since radioaactivity is a property of the atom not the molecule
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Yes it is radioactive because radioactivity is physical process that takes place at the nucleus of atoms. The caesium bonding with the chlorine doesn't affect the nucleus and it'd still be radioactive.
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yeah i think its going to b radio active because radioactivity is because of the different neutron number .. it affects the nucleus
so when caesium reacts with chlorine online electrons are involved .. the nucleus is not affected so it remains radioactive
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@twilight and hyebyekadal
The question is this that whether the compoud caesium chloride will be radioactive or not? If i haven't understood wrong then u guyz said tht the caesium will still remain radioactive and so you mean that the compoud will also be radioactive ???
Well, I thought the answer was No because... Radioactivity is a nuclear process and not a chemical reaction... while bonding with chlorine is a chemical reaction and so the compound caesium chloride will not be radioactive.
But i not sure im right or wrong ???
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ur rong itll remain radoactive.. read ur notes . or read my comment again. i have to go now.
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This is not included in IGCSE 2009 syllabus
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Chemical and radioactive process are completely independent and radioactive elements remain radioactive even when they are part of a compound
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yup .. and that's why they told u the meat was radio active .. caesium would surly b in the form of a compound in the meat
if it radioactivity would b affected by chemical reactions then the meat would not become radioactive as caesium would have gone through a series of chemical reactions in the goat's body
so it's a clue that's given that means radioactive caesium would still remain radioactive even in a compound
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twilight it is not included =\ Right right?
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OKay i got it!! ;D Thanks a lot everyone for helping me out... You all are great :)
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wut is not included sweetsh? the goat meat part ?
if u mean that then this part is in the question that naruto posted
but i meant reindeer not goat sorry ;) "In Sweden, caesium-137 built up in small plants called lichen. These plants were eaten by reindeers and gave rise to radioactive meat."
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Sorry guys it seems I misunderstood everything. I apologize im a bit tired and not okay.
Sorry again
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its ok sweetsh ;) .. i hope u get ok soon .. jst take a rest
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Thank you. Yes I should
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Q: Uranium-238 is a radio-isotope found in the Earth. It has a proton (atomic) number of 92 and a mass number of 238.
(i) Uranium-238 atoms split up to give a different element. Why do uranium-238 atoms split up? [2]
Okay i think that the answer is: Because it has unstable nuclie... so is this answer correct for a 2 marks question??
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For a 2 mark question you might say also the products have less energy than the Uranium atom had to start with.
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yeah .. and in order to reach to a more stable state
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@ astar
Sorry, but i dint understood your answer :-[ ??? If u dont mind can u plzz explain it.
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It is a fundamental principal of nature to strive for the least energy, which is why for exa,ple, balls roll down hills. When an atom splits, the two separate particles have less energy than the original atom. The difference is released as a gamma ray.
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Oh,Thanks i dint knew this principle.
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doesnt the caesium gain stability ???
sweetsh its not in the syallbus dont worry ;D.. u sittin the ig's?
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Yes I am. But I was not concentrating sorry guys I misunderstood things
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thats not CHEM!
lol is that sth from a phy paper?
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ANION TEST
Any kool ways to remember anion test for
HALIDES
NITRATE
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I dont have a "cool" way.
But its simply that:
Cl- : with HNO3 and AgNO3 -> white ppt
with HNO3 and Pb(NO3)2 -> white ppt
Br- : with HNO3 and AgNO3 -> pale yellow ppt
with HNO3 and Pb(NO3)2 -> pale yellow ppt
I-: with HNO3 and AgNO3 -> yellow ppt.
with HNO3 and Pb(NO3)2 -> yellow ppt.
For (NO3)- :
1) add NaOH
2)Add Al particles(powder foils or granuels)
3)put a damp red litmus on the mouth of the test tube.
4)warm gently
Result:
1)pungent smell
2) red litmus paper will then turn to blue
beacuase NH3 is formed
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http://www.docbrown.info/page13/ChemicalTests/GasPreparation.htm
http://www.docbrown.info/page01/ExIndChem/ExtraElectrochem.htm
this websites provides very nice explanation on various topics
http://www.chemactive.com/igcse_edexcel_chemistry.html
http://www.chemactive.com/grade_10.html
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Yes I know this website its useful.I mean the above one.
But people should know that it includes also notes out of our IGCSE syllabus. Just not to get confused
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yeah ur right ,, its not exactly our syllabus stuff .. but still u guys can study the things which are ,, it briefs them nicely
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>:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:( >:(
i am going to write this on my background!!
nice idea!
koool
:) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :)
;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;)
:D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D
;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
:o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o
8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)
:P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P :P
WHO UNderstood fuel cell?
is it there in syllabus?
i never understood it
i was taught last year
i asked soo manny ppl,
By the way i lost hope now
NO Hope
cant understand
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sgvaibhav if you noticed I answered your question above
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?? ???
i got the answer.
i am angry at that freaking aluminium powders, with those squeaky clorides and bugging bromides. they form a family of idiotic halides.
:@
but i got a kool idea
any idea how to put this as a screen saver or as a background?
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Good you did. No print them and stick them near to your bed so you dream of them =)
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can sum1 plz suggest wat parts of wich topics are important for chemistry-alternative to practical(paper 6),cuz i hv lately chnged from commerce to science. :-\cnt understand wats imp n watz with the examination point of view..
appreciated...
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Guys i need help!
1.what is da difference b/w spontinous n displacement Rx?
2.a proper defination of metallic bond like it shud include sea of electrn, latice n blah blah blah
3.IMP: ANYONE WITH ALL APPARATUS AND THEIR NAMES LIST? As this the first question in ppr6 so plz provide me sumthng a page or wateva...
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Guys i need help!
1.what is da difference b/w spontinous n displacement Rx?
2.a proper defination of metallic bond like it shud include sea of electrn, latice n blah blah blah
3.IMP: ANYONE WITH ALL APPARATUS AND THEIR NAMES LIST? As this the first question in ppr6 so plz provide me sumthng a page or wateva...
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i want to know those too .. thanks
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may you explain to me electrolysis in anyway you like to explain it. It helps me if i read someones explanation before i read the whole chapter. thanks :) oh oh..yeah may you explain acids and basis :P i get confused most of the times :-\
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i can define metallic bonding ..
METALLIC BONDING is a regular lattic arrangement of positive ions embeded in a sea of negative electrons
i hope this will do
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spontaneous reactions are reactions that occur at room temperature as their activation energy isn't very high. and displacement reactions are reactions in which a compound breaks down into 2 or more products.
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The force of attraction between of negative electrons and positive atoms
Keep everything together
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thanks ,, but there was a definition about sea of electrons or delocalised electrons i really cant find a good definition for that one ,, if some one could tell .. and please i want all the aparatus names for the practicle my book dont have all of them because i've seen some in pastpapers that are not in my book .
thanks
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may you explain to me electrolysis in anyway you like to explain it. It helps me if i read someones explanation before i read the whole chapter. thanks :) oh oh..yeah may you explain acids and basis :P i get confused most of the times :-\
Electrolysis is used to purify ores. The ore forms the anode and the pure metal the cathode. The anode is connected to the postive terminal of a battery and postive ions of the substance to be purified dissolve from it into solution and move towards the cathode.
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thanks ,, but there was a definition about sea of electrons or delocalised electrons i really cant find a good definition for that one ,, if some one could tell .. and please i want all the aparatus names for the practicle my book dont have all of them because i've seen some in pastpapers that are not in my book .
thanks
In metals, the metal atoms lose their outer electrons to form metal cations. The electrons from all the metal atoms form a "sea" of electrons that can flow around these metal cations. These electrons are often described as delocalised electrons - delocalised means "not fixed in one place" or "free to move".
Also explained more fully here.
http://www.chemguide.co.uk/atoms/bonding/metallic.html
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What abt apparatus? N Thanks 4 da other ques...