Chemistry: Post your doubts here!

[holoholo]

explanation please ?

 

[holoholo]

If i put the positive charge on the other double bonded carbon atom, is it wrong ?

 

[qwertypoiu]

View attachment 59769

If i put the positive charge on the other double bonded carbon atom, is it wrong ?

Yes that would be wrong. The other carbon atom is neutral because it is bonded to four atoms.

 

[qwertypoiu]

View attachment 59768

explanation please ?

0.1 moldm-3 solution of Fe2(SO4)3 (aq)
It will dissociate in water like this:
Fe2(SO4)3 (aq) <------> 2Fe3+ (aq) + 3SO42- (aq)
So the conc of Fe3+ ions is actually 0.2moldm-3

This will undergo hydrolysis with water, forming H+ ions as shown in the question.
So:
pH = -log(sqrt(Ka*[acid]))
Or whatever method you usually use, just make sure your conc of acid is 0.2

 

[holoholo]

Yes that would be wrong. The other carbon atom is neutral because it is bonded to four atoms.

I think you misunderstood.
I meant that in the mark scheme they put the + sign on the carbon atom with one hydrogen atom. So the Br bonded to the carbon atom with two hydrogen atoms first.
My question is if i put the +sign on the carbon atom with two hydrogen atoms and bonded the Br to the carbon with one hydrogen atom first. Would that be wrong ?

 

[qwertypoiu]

I think you misunderstood.
I meant that in the mark scheme they put the + sign on the carbon atom with one hydrogen atom. So the Br bonded to the carbon atom with two hydrogen atoms first.
My question is if i put the +sign on the carbon atom with two hydrogen atoms and bonded the Br to the carbon with one hydrogen atom first. Would that be wrong ?

Oh I see. Well I'm not sure but I think order of bonding (which carbon bromine bonds to first) should not matter.
If it does then someone else should correct me

 

[holoholo]

Oh I see. Well I'm not sure but I think order of bonding (which carbon bromine bonds to first) should not matter.
If it does then someone else should correct me

so it does not matter which double bonded carbon atom is positive ?

 

[qwertypoiu]

so it does not matter which double bonded carbon atom is positive ?

The carbon that is lacking a bond is positively charged.

 

[DeadlYxDemon]

Is it " 1,2 dimethylcyclopropane " ?

 

[qwertypoiu]

Is it " 1,2 dimethylcyclopropane " ?

View attachment 59771

Yes it is!
You can read about it here:
https://en.m.wikipedia.org/wiki/1,2-Dimethylcyclopropane

 

[sj0007]

I understand that A and C are not correct but I am confused between B and C.......... When it comes to cyclic isomers, won't propene and butene both have them?
Can anyone help me out?
Thnx

 

[Eugene99]

So I can understand that carvone is a ketone and 2-4 DNPH is a test for carbonyl group, but how will I know that what amount of molecules react with 2,4 DNPH??

 

[Eugene99]

I thought only the CH3 which is near to OH was the only chiral center, because it was the only one which was sp3 hybridizied and had four different groups attached but how is the answer D??

 

[Rizwan Javed]

View attachment 59772
I understand that A and C are not correct but I am confused between B and C.......... When it comes to cyclic isomers, won't propene and butene both have them?
Can anyone help me out?
Thnx

It can never be 6, because if you divide 6 Carbons into two molecules, each molecule will have 3 Carbons. You can't make any non-cyclic isomer out of propane. So 6 is not an option.

 

[Rizwan Javed]

I thought only the CH3 which is near to OH was the only chiral center, because it was the only one which was sp3 hybridizied and had four different groups attached but how is the answer D?? View attachment 59774

I think these all are the chiral centers for this molecule.

 

[Eugene99]

View attachment 59775
I think these all are the chiral centers for this molecule.

Can you please explain why? Shouldn't the chiral centers have four different substituent groups attached?

 

[Rizwan Javed]

View attachment 59773

So I can understand that carvone is a ketone and 2-4 DNPH is a test for carbonyl group, but how will I know that what amount of molecules react with 2,4 DNPH??

After the reaction with Concentrated, Hot, KMnO4 you get a molecule as shown above.

There're 4 carbonyl groups. 1 molecule of 2,4 DNPH reacts with 1 carbonyl. As there're are 4 carbonyl groups, so you'll need 4 molecules of 2,4 DNPH.
2,4 DNPH reacts with a carbonyl group like this:

 

[sj0007]

It can never be 6, because if you divide 6 Carbons into two molecules, each molecule will have 3 Carbons. You can't make any non-cyclic isomer out of propane. So 6 is not an option.

Ohhhhh RIGHT!
How stupid of me! XD
Thnx!

 

[Eugene99]

View attachment 59776
After the reaction with Concentrated, Hot, KMnO4 you get a molecule as shown above.

There're 4 carbonyl groups. 1 molecule of 2,4 DNPH reacts with 1 carbonyl. As there're are 4 carbonyl groups, so you'll need 4 molecules of 2,4 DNPH.
2,4 DNPH reacts with a carbonyl group like this:
View attachment 59777

thanks! I get that

 

[Eugene99]

View attachment 59776
After the reaction with Concentrated, Hot, KMnO4 you get a molecule as shown above.

There're 4 carbonyl groups. 1 molecule of 2,4 DNPH reacts with 1 carbonyl. As there're are 4 carbonyl groups, so you'll need 4 molecules of 2,4 DNPH.
2,4 DNPH reacts with a carbonyl group like this:
View attachment 59777

wait, can you tell me which reaction was that when ketone reacted with potassium manganate solution?
why was carbondioxide produced? I don't remember reading about any such reaction??