Chemistry: Post your doubts here!

[Rizwan Javed]

Anyone?View attachment 60343

When M is reacted under acidic conditions with HCl, the two reactions that occur are the hydrolysis of ester, and amide present in this compound (it has been indicated in the diagram above).

The hydrolysis of these will give you two compounds:
HO2CCH2OH and HO2CCH2NH2

As the conditions are acidic, the amine produced would be protonated under acidic conditions, giving HO2CCH2NH3+, hence the answer will be B.

 

[Eugene99]

How comes the answer is C? Silver nitrate and ammonia solution are used to test halides, not alcohols!!
a li'l explanation please!

 

[Rizwan Javed]

How comes the answer is C? Silver nitrate and ammonia solution are used to test halides, not alcohols!!
a li'l explanation please!


View attachment 60355

Silver nitrate in ammonia solution is the Tollen's reagent Instead of mentioning Tollens' reagent they mentioned its composition to confuse us

 

[nowaisir10]

Sodium hydrogencarbonate is the same as sodium bi-carbonate?

hey eugene! are you giving AS this may/june with papers 12 and 22?

 

[nowaisir10]

where

Nope I'm giving 11 and 21

do you live? aren't the students of pakistan should be giving 12 and 22?

 

[Eugene99]

Silver nitrate in ammonia solution is the Tollen's reagent Instead of mentioning Tollens' reagent they mentioned its composition to confuse us

OHH! yes!
Mr. Examiner! I remain unimpressed by your succesful attempt to confuse me

 

[Eugene99]

hey eugene! are you giving AS this may/june with papers 12 and 22?

where

do you live? aren't the students of pakistan should be giving 12 and 22?

yep, from Pakistan, and I take variant 12 and 22 but I'm practising as much as I can, because MCQs are such hell for me

 

[funky brat]

View attachment 60354
When M is reacted under acidic conditions with HCl, the two reactions that occur are the hydrolysis of ester, and amide present in this compound (it has been indicated in the diagram above).

The hydrolysis of these will give you two compounds:
HO2CCH2OH and HO2CCH2NH2

As the conditions are acidic, the amine produced would be protonated under acidic conditions, giving HO2CCH2NH3+, hence the answer will be B.

I get that. I find it a bit difficult to visualize the products tho.

 

[funky brat]

W1041 part c 2. Why does the alkene not split when the reagent used is hot KMno4?

 

[ahmedish]

W1041 part c 2. Why does the alkene not split when the reagent used is hot KMno4?

6 c ii?
It does split mate. One in the C=C, one is holding to an H, which produces COOH when ooxidised, the other is bonded to two Carbons, so it makes a ketone

 

[qwertypoiu]

can someone please explain this qs? :/

Well to be honest there isn't much explanation for this.
You just had to know that white phosphorus (the very reactive allotrope of phosphorus) is P4... A tetrahedral structure. As the mark scheme shows, you can connect them all such that each P atom has three bonds.
Over time, white phosphorus tends to change into red phosphorus. In fact, by heating up white phosphorus above 250 degrees, this process can be accelerated to form red phosphorus from white phosphorus. One of the P-P bonds in white phosphorus molecule breaks to form a bond with a neighboring P4 molecule. This is just like polymerisation. So you can show any length of this chain in your diagram.

So to summarize, white phosphorus is P4 and red phosphorus is just a bunch of P4's joined together.

As for whether this is in our syllabus, I have no idea.

 

[Lola_sweet]

Well to be honest there isn't much explanation for this.
You just had to know that white phosphorus (the very reactive allotrope of phosphorus) is P4... A tetrahedral structure. As the mark scheme shows, you can connect them all such that each P atom has three bonds.
Over time, white phosphorus tends to change into red phosphorus. In fact, by heating up white phosphorus above 250 degrees, this process can be accelerated to form red phosphorus from white phosphorus. One of the P-P bonds in white phosphorus molecule breaks to form a bond with a neighboring P4 molecule. This is just like polymerisation. So you can show any length of this chain in your diagram.

So to summarize, white phosphorus is P4 and red phosphorus is just a bunch of P4's joined together.

As for whether this is in our syllabus, I have no idea.

even i was wondering if its there :/
but thank you i understood the explanation

 

[Saad the Paki]

where

do you live? aren't the students of pakistan should be giving 12 and 22?

I'm from Pakistan but I don't live there . I'm in Saudi Arabia.

 

[totalljerkface]

Can someone please explain these polymer questions
M/j/13/41 q8 the first part
and m/j/13/42 q8 8 b(i)
URGENT !!

 

[Rizwan Javed]

Can anyone tell me from where I can practice questions relating to IR spectrometer?

 

[Kiara P.]

Can anyone tell me from where I can practice questions relating to IR spectrometer?

Have you done the book/past paper questions first?

 

[Rizwan Javed]

Have you done the book/past paper questions first?

It's a new addition to the AS syllabus, so no past papers yet. But I have done the book.

 

[ashcull14]

why do we consider 0.2moldm^-3 due to Fe3+ ions

 

[Awesome12]

View attachment 60400
why do we consider 0.2moldm^-3 due to Fe3+ ions

There are 2 iron atoms in Fe2(SO4). The reaction shown only involves 1 Iron (III) atom.

 

[ashcull14]

There are 2 iron atoms in Fe2(SO4). The reaction shown only involves 1 Iron (III) atom.

if it involves onle one Fe3+ then y do we mutiply the conc wid 2....SO42- = weak base ...it doesnt affect the pH...isnt tht so?