Chemistry: Post your doubts here!

[Ebrahim12]

amide with acid form ammonium ion not amine

"The amine formed will react with the acid to form a salt."

 

[student3737]

Damn, really? do you know how other groups compare to each other in terms of shift value/electronegativity?

The most electronegative in order
would be
abenzene ring
Then you have the CO double bond
Fluorine
Oxygen
Nitrogen

Those are all which I know of

 

[student3737]

For the addition of excess bromine , why does bromine not attack the right most end of the benzene ring ? It only reacts with the left ring, why not the right hand side ring ?

 

[Ebrahim12]

For the addition of excess bromine , why does bromine not attack the right most end of the benzene ring ? It only reacts with the left ring, why not the right hand side ring ?

You need a catalyst to substitute a halide into a benzene ring, like AlBr3. The left ring is a phenol which reacts without a catalyst.

 

[mittul8yu98]

how to deduce the rate determining step

 

[mittul8yu98]

do we need Kc and K partial pressure in A2 chemistry

 

[student3737]

Why doesn’t compound A react with Al2O3 or acidified K2Cr2O7? Shouldn’t it get oxidized ?

 

[student3737]

do we need Kc and K partial pressure in A2 chemistry

Generally yes, it’s useful to understand the concept of partial pressure , especially for paper 5, kc is extremely important for a levels , I see a lot of kc questions in the past papers,

 

[student3737]

How do you draw the repeating unit? I never seem to get these questions right, is there a certain method to use? How do you know what’s on the side chain?

 

[Ebrahim12]

how to deduce the rate determining step

I'm guessing you have the rate equation from previous parts?

The rate equation gives you the molecules involved in the rate determining step (or, if one of the reactants in the rate determining step is a product from another step and doesn't show up in the overall reaction equation, it will show the reactants that formed it) and the powers in the rate equation give the molar ratio in the rate determining step.
(this vid explains it better :

)

Why doesn’t compound A react with Al2O3 or acidified K2Cr2O7? Shouldn’t it get oxidized ?

Which paper is this?

How do you draw the repeating unit? I never seem to get these questions right, is there a certain method to use? How do you know what’s on the side chain?

Look at whats bonded to the two double bonded carbons, one has 2Hs, one has 1H and CO2H

 

[student3737]

I'm guessing you have the rate equation from previous parts?

The rate equation gives you the molecules involved in the rate determining step (or, if one of the reactants in the rate determining step is a product from another step and doesn't show up in the overall reaction equation, it will show the reactants that formed it) and the powers in the rate equation give the molar ratio in the rate determining step.
(this vid explains it better :

)


Which paper is this?

It’s summer 2013 variant 41

Look at whats bonded to the two double bonded carbons, one has 2Hs, one has 1H and CO2H

 

[Ebrahim12]

Why doesn’t compound A react with Al2O3 or acidified K2Cr2O7? Shouldn’t it get oxidized ?

Al2O3 is a reducing/dehydrating agent, so it wouldn't react.

We only have oxidation of alkyl benzene by KMnO4, so you have to say no reaction.

 

[student3737]

Al2O3 is a reducing/dehydrating agent, so it wouldn't react.

We only have oxidation of alkyl benzene by KMnO4, so you have to say no reaction.

So which groups do Cr2O7 oxidize ?

 

[blymphocytes]

Hy everyone,

Could anyone please upload the 2019 feb-march ppr 4? or atleast send me a link ...thank you!

 

[student3737]

Guys how do you solve this buffer solution question?

 

[mittul8yu98]

So which groups do Cr2O7 oxidize ?

kmno4 only oxidises only groups bonded to benzene

 

[mittul8yu98]

I'm guessing you have the rate equation from previous parts?

The rate equation gives you the molecules involved in the rate determining step (or, if one of the reactants in the rate determining step is a product from another step and doesn't show up in the overall reaction equation, it will show the reactants that formed it) and the powers in the rate equation give the molar ratio in the rate determining step.
(this vid explains it better :

)


Which paper is this?



Look at whats bonded to the two double bonded carbons, one has 2Hs, one has 1H and CO2H

thanks man

 

[mittul8yu98]

sw

Guys how do you solve this buffer solution question?

which year

 

[student3737]

sw


which year

2013 summer

 

[student3737]

I'm guessing you have the rate equation from previous parts?

The rate equation gives you the molecules involved in the rate determining step (or, if one of the reactants in the rate determining step is a product from another step and doesn't show up in the overall reaction equation, it will show the reactants that formed it) and the powers in the rate equation give the molar ratio in the rate determining step.
(this vid explains it better :

)


Which paper is this?



Look at whats bonded to the two double bonded carbons, one has 2Hs, one has 1H and CO2H

But what about this structure ? I got CH2-CH-COOH as the monomer but the marking scheme says CH2=CH-COOH, why is there a double bond?