Chemistry: Post your doubts here!

[Saad the Paki]

In which reaction does a single nitrogen atom have the greatest change in oxidation number?
A 4NH3 + 5O2 --> 4NO +6H20
B 3NO2 + H2O -->2HNO3 +NO
C 2NO +O2 --> 2NO2
D 4NH3 +6NO -->5N2 + 6H2O

The answer is A.
I'm confused at B where 2 products have N in them. Are we supposed to add their oxidation states (HNO3 AND NO)? Similarly at D where both reactants have N.
Please help, thank you!

The question asks for a SINGLE nitrogen atom. So no u don't add them up, you have to compare them separately, first compare NO2 with HNO3 then compare NO2 with NO, but neither of them give the largest change separately. Same way for D

 

[drowning-in-studies]

The question asks for a SINGLE nitrogen atom. So no u don't add them up, you have to compare them separately, first compare NO2 with HNO3 then compare NO2 with NO, but neither of them give the largest change separately. Same way for D

Thank you!!

 

[Copy Cat]

 

[Awesome12]

View attachment 59582

24) The molecule could either be an ALCOHOL or an ETHER. It cannt be an ALDEHYDE or any other molcule with a carbonyl or carboxylic group. Thus (1) is not possible as the reaction can only happen if the molecule was an aldehyde, which it isnt.
(2) this could be possible in the case of an ether or TERTIARY ALCOHOL. It does not show a positive test with DNPH or TOLLENS REAGENT. It can also not be oxidized.
(3) this could be possible in the case of an PRIMARY OR SECONDARY ALCOHOL. It could be oxidized to an aldehyde and ketone respectively.

25) (1) An Aldehy will react with Fehlings Reagent. The Cu+2 ions are reduced whilst the aldehyde is oxidized to carboxylate ion
(2) this is a free radical substituion reaction. No oxidation and reduction whatsoever
(3) Reaction does not even take place

 

[Rizwan Javed]

(2) this is a free radical substituion reaction. No oxidation and reduction whatsoever

The reaction of CH4 and Cl2 is a redox reaction.
Consider this equation: CH4 + Cl2 ---> CH3Cl + HCl
In this equation, Cl goes from 0 to -1 oxidation state, and C goes from -4 to -2. So it IS a redox reaction.

Thus both 1, 2 are correct.

 

[Awesome12]

The reaction of CH4 and Cl2 is a redox reaction.
Consider this equation: CH4 + Cl2 ---> CH3Cl + HCl
In this equation, Cl goes from 0 to -1 oxidation state, and C goes from -4 to -2. So it IS a redox reaction.

Thus both 1, 2 are correct.

Oh yeah lol. I was thinking of it as the reactions taking place in the intermediate steps of substitution of Alkanes

 

[Syed Umar]

Okay, thanks!

It's C because it has an odd number of electrons- 15.

 

[Copy Cat]

Oh yeah lol. I was thinking of it as the reactions taking place in the intermediate steps of substitution of Alkanes

The reaction of CH4 and Cl2 is a redox reaction.
Consider this equation: CH4 + Cl2 ---> CH3Cl + HCl
In this equation, Cl goes from 0 to -1 oxidation state, and C goes from -4 to -2. So it IS a redox reaction.

Thus both 1, 2 are correct.

24) The molecule could either be an ALCOHOL or an ETHER. It cannt be an ALDEHYDE or any other molcule with a carbonyl or carboxylic group. Thus (1) is not possible as the reaction can only happen if the molecule was an aldehyde, which it isnt.
(2) this could be possible in the case of an ether or TERTIARY ALCOHOL. It does not show a positive test with DNPH or TOLLENS REAGENT. It can also not be oxidized.
(3) this could be possible in the case of an PRIMARY OR SECONDARY ALCOHOL. It could be oxidized to an aldehyde and ketone respectively.

25) (1) An Aldehy will react with Fehlings Reagent. The Cu+2 ions are reduced whilst the aldehyde is oxidized to carboxylate ion
(2) this is a free radical substituion reaction. No oxidation and reduction whatsoever
(3) Reaction does not even take place

Thanks

 

[Copy Cat]

 

[Dark Destination]

View attachment 59586

B? That shows two p orbitals overlapping parallely.

 

[Copy Cat]

B? That shows two p orbitals overlapping parallely.

Correct me If I am wrong but P-orbital have a dumb-bell shaped.Right?
The Answer is B.

 

[Dark Destination]

Correct me If I am wrong but P-orbital have a dumb-bell shaped.Right?

Yes.

 

[Copy Cat]

M/J/12/22 Q3 d(ii) & (e)

 

[Copy Cat]

Yes.

Then why not D?

 

[Dark Destination]

Have there been many significant changes in the syllabus for 2016? Like are a lot of things removed from the syllabus or added?

 

[Dark Destination]

Then why not D?

I don't even know what the hell kinda orbitals are shown in D, but it seems odd. B seems like two P orbitals overlapping parallel.

 

[FranticAmaze]

Have there been many significant changes in the syllabus for 2016? Like are a lot of things removed from the syllabus or added?

Yes both...group 4 is removed..I think group 5 was also there before and is removed, a lotta of DNA part is removed, competitive and non competitive enzymes part removed
Carbon13 Nmr, organic synthesis, Nernst equation,Gibbs free and entropy amongst others are added

 

[My Name]

Yes both...group 4 is removed..I think group 5 was also there before and is removed, a lotta of DNA part is removed, competitive and non competitive enzymes part removed
Carbon13 Nmr, organic synthesis, Nernst equation,Gibbs free and entropy amongst others are added

I wish you said Gibbs and Nernst were removed.:/

 

[Dark Destination]

Yes both...group 4 is removed..I think group 5 was also there before and is removed, a lotta of DNA part is removed, competitive and non competitive enzymes part removed
Carbon13 Nmr, organic synthesis, Nernst equation,Gibbs free and entropy amongst others are added

Where to study these topics from? :/

 

[FranticAmaze]

I wish you said Gibbs and Nernst were removed.:/

Lol its easy only