Chemistry: Post your doubts here!

[Hamnah Zahoor]

And one more thing can sulfuric acid dehydrate carboxylic acid?

No I don't think so.
Also If dehydration would occur it would have been then shown in the Q: 25 discussed above.

 

[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 11
First balance the equation using oxidation states
5Sn(2+) + 2Mn(7+) ---------> 5Sn(4+) + 2Mn(2+)
moles of Sn= 0.05
0.05*(2/5) = 0.02 mol
thus option B

Q 24
Option D first add potassium cyanide ( better than HCN )
it will substitute Chlorine with CN
as we need to add one more Carbon in the chain
then for hydrolysis NaOH will be added to form the given product.

Q 27
When alkaline aqueous iodine is treated with 3 methyl butane it will form the following product.

Na will not be included as it only states alkaline not mentioned specific.

Q 30
Double bond is more stronger than single thus in poly(ethene) bonds are weaker and more weaker the bond is more longer it is.

 

[MShaheerUddin]

Yeah I understand what u r saying but what will be the final equation? It is not balancing using these figures

The simplest ratio of 4:2 is actually the value of n and p
These value are find using the above method
Then we would balance q
Finally we will balance the reactants (m)

This is the typical method followed when balancing the equation using Valancies
Turn to page 112 of the book and see worked examples

 

[zap-cannon]

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

 

[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?