Qualification > Sciences
ALL CIE CHEMISTRY DOUBTS HERE !!
Deadly_king:
--- Quote from: Kirin on December 07, 2010, 01:04:00 pm ---Dude, the answer is 17 C.
Anyways, how is it C ? What does option C even mean ?
--- End quote ---
Ooh yeah.......i'll modify my post. :-[
elemis:
--- Quote from: Martin Luther King Jr on December 07, 2010, 12:52:24 pm ---Bond energy for H-Cl is greater since Cl is a smaller atom, hence force of attraction will be greater. ;)
--- End quote ---
H-Cl has a shorter bond length than H-I therefore it is stronger and hence requires greater energy to break the bond, right ?
Deadly_king:
--- Quote from: Kirin on December 07, 2010, 01:50:35 pm ---H-Cl has a shorter bond length than H-I therefore it is stronger and hence requires greater energy to break the bond, right ?
--- End quote ---
You're absolutely correct br0 :D
elemis:
http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s03_qp_1.pdf
Q33
http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_w03_qp_1.pdf
Q2
Deadly_king:
--- Quote from: Kirin on December 08, 2010, 11:03:07 am ---http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s03_qp_1.pdf
Q33
http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_w03_qp_1.pdf
Q2
--- End quote ---
Jun 03 p1 No 33
It is given that the conversion of graphite to diamond is endothermic.
1. The enthalpy change of atomisation of diamond is smaller than that of graphite -----> It is correct since converting graphite to diamond is endothermic meaning graphite requires more energy.
2. The bond energy of the C-C bonds in graphite is greater than that in diamond -----> It is correct as well since in diamond, each carbon carries 4 bonds while in graphite they carry only 3 bonds.
3. The enthalpy change of combustion of diamond is greater than that of graphite -----> It is correct too dor the same reason as the first one.
So answer is A.
Nov 03 p1 No 2
First you need to find the % of phosphorus in P2O5 ----> 2(31)/142 x 100 = 43.7 %
It is given that P2O5 is 30% of the fertiliser. Hence phosphorus will be 43.7% of this 30%.
% by mass of phosphorus = (43.7/100 x 30/100)/1 x 100 = 13.1%
Therefore answer is B.
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