Chemistry: Post your doubts here!

[nehaoscar]

Can some one explain Q26 please! View attachment 57737

To form a diol, the carbon next to the alkene needs to have atleast one hydrogen attached to it. So A and D are wrong.
To form a ketone, you need a secondary alcohol i.e 1H and 2R groups attached to the carbon with the OH
To give a di-ketone, both the carbons with OH must be secondary alcohols
This is seen in C so it's C.

 

[Bah...]

Hello, does anyone have s02 qp1? I need it ASAP.
Thanks in advance

 

[Anum96]

Hello, does anyone have s02 qp1? I need it ASAP.
Thanks in advance

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_s02_qp_1.pdf

 

[Bah...]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_s02_qp_1.pdf

Thank you so much, Anum!

 

[***amd***]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s15_qp_12.pdf
Q12

 

[phanttasy]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s15_qp_12.pdf
Q12

see attachment for the explanation
hope you can understand

 

[***amd***]

see attachment for the explanation
hope you can understand

thanks

 

[ashcull14]

 

[qwertypoiu]

View attachment 57782

Let CH3CO2H = x cm3
Let CH3CO2Na = (100-x) cm3

pH = pKa + log(salt/acid)

5.5 = -lg(1.79E-5) + log(salt/acid)
5.5 = 4.75 + log(salt/acid)
log(salt/acid) = 0.75
Salt/acid = 0.1778
(100-x)/x = 0.1778
100-x = 0.1778x
100 = 1.1778x
x = 100/1.1778 = 85
100-x = 15

 

[ashcull14]

Let CH3CO2H = x cm3
Let CH3CO2Na = (100-x) cm3

pH = pKa + log(salt/acid)

5.5 = -lg(1.79E-5) + log(salt/acid)
5.5 = 4.75 + log(salt/acid)
log(salt/acid) = 0.75
Salt/acid = 0.1778
(100-x)/x = 0.1778
100-x = 0.1778x
100 = 1.1778x
x = 100/1.1778 = 85
100-x = 15

thanks

 

[My Name]

http://maxpapers.com/wp-content/uploads/2012/11/9701_s13_qp_23.pdf
question 5 part a iv

 

[The Sarcastic Retard]

http://maxpapers.com/wp-content/uploads/2012/11/9701_s13_qp_23.pdf
question 5 part a iv

2 products. One will be organic and other is CO2.
Organic product will be HO2CCO2H (Break the alkene, you get CHO it further oxidises to COOH and OH is oxidised to COOH as well)

 

[My Name]

2 products. One will be organic and other is CO2.
Organic product will be HO2CCO2H (Break the alkene, you get CHO it further oxidises to COOH and OH is oxidised to COOH as well)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s13_ms_22.pdf
question 4 part a
product of
C if I write CH3(CH2)2CH2OH instead of CH3CH2CH2CH2OH
and product of
E if I write CH3CH=CHCOOH instead of CH3CH=CHCO2H

Fine?

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w09_ms_22.pdf
question5 part b
for equation if I CH3CH2CH2CH2OH instead of C4H9OH

Fine?

 

[Saad the Paki]

Help with this question please

 

[My Name]

Help with this question please View attachment 57985

I think it is A.
What is your doubt?
About whether it is A or B?

 

[Metanoia]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s13_ms_22.pdf
question 4 part a
product of
C if I write CH3(CH2)2CH2OH instead of CH3CH2CH2CH2OH
and product of
E if I write CH3CH=CHCOOH instead of CH3CH=CHCO2H

Fine?

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w09_ms_22.pdf
question5 part b
for equation if I CH3CH2CH2CH2OH instead of C4H9OH

Fine?

Yes. What you've written is fine.

 

[Saad the Paki]

I think it is A.
What is your doubt?
About whether it is A or B?

The answer is A
But yes I'm confused between A or B... even D seems likely
Can u point out some reasons why the Ans is A and not B or D

 

[My Name]

The answer is A
But yes I'm confused between A or B... even D seems likely
Can u point out some reasons why the Ans is A and not B or D

It can't be D since I don't think that an ester can dissolve in water completely.
Then you have A and B.
It can't be B since alcohols are not acidic enough to react with aqueous solutions of strong alkalis.( However,they can react with the recatice metals.)

 

[Saad the Paki]

It can't be D since I don't think that an ester can dissolve in water completely.
Then you have A and B.
It can't be B since alcohols are not acidic enough to react with aqueous solutions of strong alkalis.( However,they can react with the recatice metals.)

Ooh okay..! Thanks

 

[My Name]

Ooh okay..! Thanks

Welcome