Chemistry: Post your doubts here!

[Hamnah Zahoor]

View attachment 63883 View attachment 63884 View attachment 63885 View attachment 63886 View attachment 63887 I need help with these.

Can anyone explain why 30 isn’t C. According to what I’ve learnt about sigma bonds, 30 should be C.

Q: 3

 

[Hamnah Zahoor]

View attachment 63957

can anyone please explain ?? I thought D because the product will be ch3co2H ( addition of oxygen is oxidation )

D is not oxidation it is hydrolysis.
Whereas Option B shows oxidation where the tollen reagent oxidises the aldehyde to carboxylic acid.

 

[khadijaimran]

how come the ans is D? why not B? please explain.

 

[Hamnah Zahoor]

how come the ans is D? why not B? please explain.

I hope it is understandable If you don't get it do let me know.

 

[khadijaimran]

im sure that A is wrong what about the rest, all of them are secondary alcohols and form geometric isomers.
the correct ans is C

 

[khadijaimran]

I hope it is understandable If you don't get it do let me know.
View attachment 63974

aahh i get it thanks

 

[MShaheerUddin]

im sure that A is wrong what about the rest, all of them are secondary alcohols and form geometric isomers.
the correct ans is C

Because only C has "CH(OH)CH3" group of alcohol which reacts with aqueous alkaline only when we talk about alcohol. note it down

 

[khadijaimran]

Because only C has "CH(OH)CH3" group of alcohol which reacts with aqueous alkaline only when we talk about alcohol. note it down

secondary alcohols dont react then?

 

[MShaheerUddin]

secondary alcohols dont react then?

This is secondary alcohol but the point is, the sec alcohol must be like this ... "CH(OH)CH3" [Methyl group attached to the same carbon which is attached with OH group]

 

[MShaheerUddin]

Can anybody explain this to me?
Ans is B

 

[Hamnah Zahoor]

View attachment 63976
Can anybody explain this to me?
Ans is B

Carbon should be labelled.
And for carbon atoms to be in the same plane the angle between them should be 120 degrees.

 

[MShaheerUddin]

Carbon should be labelled.
And for carbon atoms to be in the same plane the angle between them should be 120 degrees.
View attachment 63981

what about middle carbon in 3
It also has 3 bonds and 0 lonepair (120)

 

[Hamnah Zahoor]

what about middle carbon in 3
It also has 3 bonds and 0 lonepair (120)

You mean this:

At this carbon angle is 109.5

 

[MShaheerUddin]

Ohhh
You are so genius hats off

 

[Hamnah Zahoor]

Ohhh
You are so genius hats off

Thankyou.

 

[MShaheerUddin]

THis?

 

[Hamnah Zahoor]

View attachment 63984

THis?

For statement 1 The following website will help you understand it in a more better way
https://www.chemguide.co.uk/mechanisms/nucadd/hcn.html

Thus, Statement 1 correct.

For statement 2 :
The initiating step is the nucleophile CN- attacking the partial positive carbon NOT the proton (H+) being transferred to oxygen.
For statement 3 :
Only aldehydes or ketone react with the Cyanide ion not esters. ( thus only one group reacts)

 

[MShaheerUddin]

 

[Hamnah Zahoor]

View attachment 63985

I hope the following structure will help you name the product more easily. Option B

 

[MShaheerUddin]

Thank you so much
Are you a graduate?