Qualification > Sciences
IG Chemistry Paper 3 discussion
nid404:
--- Quote from: .... on June 03, 2009, 12:56:09 pm ---bromine? How many different variants were there? :P
well..it depends on the mole ratio..
for example, in my paper, it was 0.08 moles of silicon reacts with 7.2g of fluorine, the equation given was
Si + 2F2 ----> SiF4
so, silicon and fluorine are in the mole ratio 1:2
the moles of fluorine given is 7.2/(19x2) = 7.2/38 = 0.189 moles....(we use 38, cuz its diatomic, so we take double the original Ar
so that means, if fluorine is 0.189 moles, then according to the mole ratio, silicon should be 0.189/2 = 0.095 moles...but it is 0.08..meaning, silicon is limiting..
--- End quote ---
I took the mole ratio(1:2)
so if silicon was 0.08 then fluorine needed was 0.16(0.08x2) which is 0.16x38g(6.08g)
but there was 7.2g, much more than required ans so silicon limiting reagent
different approach but yeah same ans
LoCo93:
--- Quote from: Roxy on June 02, 2009, 02:06:05 pm ---yeah loco.. I rote silion too... itt had the least amount of moles...
--- End quote ---
ROCK ON!!! =] ;D
crypsAnity:
ahahaha.. yeah n i found that flourine was in excess.. n i knew ahd to rite the oppsite of what i find in excess.. but nawwsss had to be me n rote flourinee! yayyyy .. sighs ..
LoCo93:
--- Quote from: thukon on June 02, 2009, 02:33:44 pm ---
--- Quote from: LoCo93 on June 02, 2009, 01:42:54 pm ---i rote sumthin like add a magneisum (or any metal) ribbon and if its acidic it'll react.. ??? ??? ::) dont kno tho..
--- End quote ---
But GUYS.... the question asked how you could determine the compounds contained the same COOH group!! Just because it reacts with a base or a carbonate wont tell that its a COOH group.
--- End quote ---
naa m tlkin abt the one with tells us how do u tell if its an acid.. <3 i gues ther was a different one either that or i totali screwd up :-\
crypsAnity:
errr.. hold on a sec.. there was no question as far as i can remember which wanted to know if it COOH group.. what this? .. it asked about how would u determine ts an acid.. hmmm if thts wht ur talkign abt..
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