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Chemistry: Post your doubts here!

Daniel Jeng

Daniel Jeng

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i_try9621 said:
Anyone please help me with V and W ? Shouldn't Oxygen be replace with O-H bond ? View attachment 62717 View attachment 62718
Click to expand...

In this question test 1 is for the basic identification of whether the substance is an amide or amine. Since M does not react with the acid, this means that the substance must contain an amide group (it is neutral). Since the only other group we know containing nitrogen is amine, and it would react with the acid, we can safely assume the other substances all contain an amine group. In terms of test 5, it can test for either a hydroxy group, an acid, nucleophilic substitution or hydrolysis. remember that either an acid or an alkali can be used in hydrolysis. For the reaction with M, you should be able to see that the amide has hydrolysed into phenylamine and sodium propanoate.

EDIT: My bad, this is for the second question
 
i_try9621

i_try9621

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Daniel Jeng said:
In this question test 1 is for the basic identification of whether the substance is an amide or amine. Since M does not react with the acid, this means that the substance must contain an amide group (it is neutral). Since the only other group we know containing nitrogen is amine, and it would react with the acid, we can safely assume the other substances all contain an amine group. In terms of test 5, it can test for either a hydroxy group, an acid, nucleophilic substitution or hydrolysis. remember that either an acid or an alkali can be used in hydrolysis. For the reaction with M, you should be able to see that the amide has hydrolysed into phenylamine and sodium propanoate.

EDIT: My bad, this is for the second question
Click to expand...
Thanks for that
 
Bishnu Dev

Bishnu Dev

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Why is the percentage uncertainty in 1 C (ii) is 3?
I got 1%
 

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i_try9621

i_try9621

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Bishnu Dev said:
bro please help.... i have posted the question above this post..........
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(0.5-0)/50 = 0.01 x 100 = 1%
We used the measuring cylinder to transfer 150cm^3 of Hydrogen Peroxide so each time there is an uncertainty of 1% . In this case , it's 3 times so it's 3%
 
Bishnu Dev

Bishnu Dev

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Coolio_777 said:
View attachment 62740

w16 p11

help?
Click to expand...
The answer is A....
Take a look at bond angle X, the Nitrogen atom makes three bonds which suggests us that the bond angle should be around 120 degree but don't forget about the lone pair on Nitrogen atom which pushes the bonds even closer to each other as lone pair to bond pair repulsion is more significant. So angle X would be around 107 degrees.
Now If we talk about angle Y, there're are four groups attached to Carbon atom so it makes tetrahedral structure with a bond angle of 109.5 which is greater than X. Look, this one is different from angle X because it doesn't involve any lone pairs; and bond pair to bond pair repulsion is not as significant as lone pair to bond pair.
Angle Z is totally clear, there's no lone pair on carbon atom and it makes only three bonds among which one is double bond so we expect the angle to be around 120 degrees. Hence the answer is A
 
Daniel Jeng

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Coolio_777 said:
View attachment 62748

9701/11 w16

answer is B but how
Click to expand...
You may have thought that there would only be 3 isomers instead of 4 isomers, however there is an extra twist to this question: there are two isomers for the variation in which 2 chloro groups are next to each other. The chloro groups may bond to neighbouring carbon atoms that have a double bond between them, or a single bond. In addition to the 2 other isomers with 1 carbon in between and 2 carbons in between, you will get 4 isomers instead of 3.
 
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