Qualification > Sciences
ALL CIE CHEMISTRY DOUBTS HERE !!
Hypernova:
--- Quote from: moon on November 12, 2010, 01:37:06 am ---plzzzzzzzzz help me in these questions. :-[ :-[June 07 Q 1, 9
June 01 Q6,11,37
June 2002 Q 38
I would really apreciate any help. thanx a lot. :)
--- End quote ---
June 07 Q 1, 9
2.
Relative atomic mass is the average mass of an element compared to that of carbon 12
You need to find the average mass of the element using its reative abundance, so
Ar=10 x 1/5 + 11 x 4/5
=10.8
9.
Kc of a reaction is equal to the product of consentration of products over the product of concentration of reactants all raised to their stochiometric coefficients
so Kc for reaction 1 is 2
Kc=[X2Y]2
[X2]2x[Y2]
Know you have an equation for kc of reaction 1
The queation is find Kc for reaction 2
? = [X2]x[Y2]1/2
[X2Y]
Take your equation for kc of reaction 1 and make it look like the Kc equation for reaction 2
2=[X2Y]2
[X2]2x[Y2]
the reciprocal looks like
1 = [X2]2x[Y2]
2 [X2Y]2
now square root it
1 = [X2]x[Y2]1/2
sqrt(2) [X2Y]
so Ans is A
Hypernova:
--- Quote from: moon on November 12, 2010, 01:37:06 am ---plzzzzzzzzz help me in these questions. :-[ :-[June 07 Q 1, 9
June 01 Q6,11,37
June 2002 Q 38
I would really apreciate any help. thanx a lot. :)
--- End quote ---
I dont have June 01 paper 1, could you please upload it
Q38
For this reaction you need to know what is happening
Br2 will be attracted to the double bonds and it will become polar. Then 1 Br atom binds across the double bond, and the other has a negative charge.
This is the bromination mechanism used in the test for alkenes, I assume you know it, I will elaborate if you ask.
So then the transition state (attached) for alkene is formed.
There are charged particles in solution:
the Cl- from NaCl
The other Br- atom from Br2
these atoms are negatively charged
Notice the positively charged C+ atom in the ethene transition state (attached). It will bind to one of these charged particles.
So
1 CH2ClCH2Cl impossible
2 CH2BrCH2Cl possible
3 CH2BrCH2Br possilbe
Ans is C
moon:
Thank u so much hypernova By the way for june 2001 i have hard copy so i can't upload it sorry :-\.
Deadly_king:
--- Quote from: moon on November 12, 2010, 05:12:50 pm ---Thank u so much hypernova By the way for june 2001 i have hard copy so i can't upload it sorry :-\.
--- End quote ---
Post the whole question then ;)
We'll try to help as mush as we can. :)
moon:
I have attached June 2001 as well as November 2001.It seems that these exams are difficult to find so i thought these might help you practice more questions. Best wishes ;) :)
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