ALL CIE CHEMISTRY DOUBTS HERE !!

[Amelia]

November 2007 Paper1 Q 5, 9, 21 and 32.

Please help!

Q5 - as you know already is A.

Q9 - It's B. The 50 cm³ metal salt reacted with 25 cm³, so the oxidation state will be 1:1. The orginal oxidation state was +3, hence, the new state will be +2.

Q21 - It's A. (Ch₃)₄Pb, supplies methyl radicals. And we do require methyl radicals to react with chlorine to give off the products.

Q32 - It's A. All three options are right. *Carbon monoxide is a strong reducing agent because it is easily oxidised to carbon dioxide - where the oxidation state is the more thermodynamically stable +4.

[iluvme]

Thanks Lia and Emo.

Though I yet didn't get Q9 :/

[aneeta]

Does any one know where I can get chemistry past papers, paper 1 2000?

[EMO123]

Does any one know where I can get chemistry past papers, paper 1 2000?

of Cie AS levels is it there
i dont think so

Thanks Lia and Emo. Smiley

Though I yet didn't get Q9 :/

ohh i also dint get that so not posted

[iluvme]

I've got more doubts, Can somebody please explain?

June 2009, Paper 1
10
11
15
18
20
29
30
38 and
40

Thank You

[iluvme]

WOAH ! That's a lot. I'll see if I can provide you with some hints.

Thanks.

[elemis]

Question 10

A catalyst serves to LOWER the activation energy... does that help ?

Question 40

Alkaline Hydrolysis gives you the Sodium salt and the alcohol

Question 38

To determine if Option 1 is correct, look at the double bonds and the alcohol group at the end. KMnO4 would oxidise the alcohol to what ? An aldehyde or a ketone ? If you cant tell, then look at the no. of carbons the hydroxyl group is joined to.

Next, look at the double bonds. Can you see a place where a secondary alcohol (which upon further oxidation would form a ketone) could forrm as a result of oxidation by KMnO4 ?

Option 2 should be easy to prove/disprove.

Option 3 - Hint: Can you see any carboxylic acid groups ?

[elemis]

Question 30

It is a liquid at room temperature and atmospheric pressure.

Ethane is a gas and the others are liquids.

It does not mix completely with water.

To mix with water you need to be able to form hydrogen bonds. This statement implies that the mystery compound DOES NOT form hydrogen bonds.

It does not decolourise acidified potassium manganate(VII).

The mystery compound will not undergo oxidation.

Question 29

There is no easy way to solve these kind of questions. Just draw out the structures and see if it helps.

[iluvme]

Question 10

A catalyst serves to LOWER the activation energy... does that help ?

Question 40

Alkaline Hydrolysis gives you the Sodium salt and the alcohol

Question 38

To determine if Option 1 is correct, look at the double bonds and the alcohol group at the end. KMnO4 would oxidise the alcohol to what ? An aldehyde or a ketone ? If you cant tell, then look at the no. of carbons the hydroxyl group is joined to.

Next, look at the double bonds. Can you see a place where a secondary alcohol (which upon further oxidation would form a ketone) could forrm as a result of oxidation by KMnO4 ?

Option 2 should be easy to prove/disprove.

Option 3 - Hint: Can you see any carboxylic acid groups ?

Q 10, Energy is more at Ea1, which means activation energy is more? so uncatalysed reaction. Righto

Q 40, I was confused about the word partial. :/

Q 38, Right right right, Didn't notice that part, about COOH being absent.

[iluvme]

Question 30

It is a liquid at room temperature and atmospheric pressure.

Ethane is a gas and the others are liquids.

It does not mix completely with water.

To mix with water you need to be able to form hydrogen bonds. This statement implies that the mystery compound DOES NOT form hydrogen bonds.

It does not decolourise acidified potassium manganate(VII).

The mystery compound will not undergo oxidation.

Question 29

There is no easy way to solve these kind of questions. Just draw out the structures and see if it helps.

Right, got both.
Though Q 29, I got mixed up with the (CH₃)₂C(OH) part.

Thanks Ari.

[HUSH1994]

Question 10

A catalyst serves to LOWER the activation energy... does that help ?

Question 40

Alkaline Hydrolysis gives you the Sodium salt and the alcohol

Question 38

To determine if Option 1 is correct, look at the double bonds and the alcohol group at the end. KMnO4 would oxidise the alcohol to what ? An aldehyde or a ketone ? If you cant tell, then look at the no. of carbons the hydroxyl group is joined to.

Next, look at the double bonds. Can you see a place where a secondary alcohol (which upon further oxidation would form a ketone) could forrm as a result of oxidation by KMnO4 ?

Option 2 should be easy to prove/disprove.

Option 3 - Hint: Can you see any carboxylic acid groups ?

+rep,man your explanations are really amazing

[EMO123]

I've got more doubts, Can somebody please explain?

June 2009, Paper 1
10
11
15
18
20
29
30
38 and
40

Thank You

Question 11

3N₂ is not really much unreactive gas but in this case they are unreactive gas
but my doubt is from the last two equations which is correct
plzz explain

i also need help in Q 15

in Question 18
i got the residue as Fe(OH)₂
but i dint get the gas as NH₃ i got it as SO₂

and also need help in Q 20

[HUSH1994]

in Q15,the AgCl is insoluble,so a reaction with a more reactive metal causes Ag's displacement(from AgCl to NaCl).
Q20 : the compound has 3 double bonds,therefore you use 2 to the power of 3 which is equal to 8.

[EMO123]

Question 11

3N₂ is not really much unreactive gas but in this case they are unreactive gas
but my doubt is from the last two equations which is correct
plzz explain

i also need help in Q 15

in Question 18
i got the residue as Fe(OH)₂
but i dint get the gas as NH₃ i got it as SO₂

and also need help in Q 20

in Q no. 11
as said that only the heat is evolved and and an unreactive gas i produced
that means that it just forms an unreactive gas as it is the same o the option C is the correct answer

in Q no. 15
at some extend you are right only hush
and one more thing in it is that ions are always in aqueous forms so they are soluble so the answer for this is A

in Q no. 18
it is that as it is given that and alkaline solution is formed so it can be only NH₃
and for the solid residue is Fe(OH)2 because it is given that one cation is Fe2+ and the other thing given is it is soluble in water so it will form a hydroxide so the answer for it is C.

hope it helps
and well triad Hush

[EMO123]

for Q no 20
may be this helps
http://www.chemguide.co.uk/basicorg/isomerism/geometric.html#top