Chemistry: Post your doubts here!

[bakhita]

I have the first edition of that book, too. It's orange.
Some of the concepts for the 2016 syllabus are missing in the first edition book, though.

Yeah...you'r right! Some of the points for 2016 syllabus are missing in the 1st edition. so which one do you decide to use?

 

[Dark Destination]

Yeah...you'r right! Some of the points for 2016 syllabus are missing in the 1st edition. so which one do you decide to use?

Definitely not the orange one.

Either the second edition of that, or the red one you suggested. :3

 

[Mr.Physics]

What will be the equation for the reaction between solid lithium chloride and concentrated sulfuric acid ?

 

[bakhita]

What will be the equation for the reaction between solid lithium chloride and concentrated sulfuric acid ?

LiCl (s) + H2SO4 (aq) --> HCl (g) + LiHSO4 (aq)

 

[Mr.Physics]

LiCl (s) + H2SO4 (aq) --> HCl (g) + LiHSO4 (aq)

Thanks.
But could you explain me using an ionic equation?
The half ionic equation for the concentrated H2SO4 is

2H2SO4 + 2e ----->( SO4)-2 + 2H2O + SO2

So where do H2O and SO2 go ?

 

[Saad the Paki]

Can anyone explain how the answer is C? It's says constant speed so shouldn't kinetic energy be constant as well?

 

[Metanoia]

Thanks.
But could you explain me using an ionic equation?
The half ionic equation for the concentrated H2SO4 is

2H2SO4 + 2e ----->( SO4)-2 + 2H2O + SO2

So where do H2O and SO2 go ?

You are using a half equation where the concentrated sulfuric acid acts as an oxidizing agent. That does not happen with chlorides (i.e. LiCl).

 

[Mr.Physics]

Can anyone explain how the answer is C? It's says constant speed so shouldn't kinetic energy be constant as well? View attachment 57605

Gravitational energy changes to kinetic energy i think

 

[kayannush99]

Hi, I have a chemistry exam tomorrow. Could someone please explain the answer to Q5, 6, 9, 10, 31, 34 and 35.

Here's the link:
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_qp_12.pdf

 

[Sarosh Jameel]

PLZ help me with this! i am unable to questions of polymerisation this is may june 08 !

 

[sj0007]

Will this be the structure of the product when 2-hydroxypropanoic acid reacts with propanoic acid?

 

[qwertypoiu]

Will this be the structure of the product when 2-hydroxypropanoic acid reacts with propanoic acid?
View attachment 57700

Seems correct to me.

 

[sj0007]

Seems correct to me.

Oh hiiiiiiiii!
Thnx........ U helped me out in my IGCSE too!

 

[A*(a*)]

these are the best past papers I came across during my A levels, I do recommend them to everyone, classified past papers upto 2015 with variants included,
https://payhip.com/b/LUjF

 

[Dark Destination]

So what exactly do we have to study to prepare for Paper 4?
Does it include both AS and A2 concepts, or just A2 ones?

For example, do i need to just study A2 organic chemistry (Benzene etc.) or the entire AS organic chemistry as well?

 

[nehaoscar]

Can anyone explain how the answer is C? It's says constant speed so shouldn't kinetic energy be constant as well? View attachment 57605

The answer is not C, it's B ... check the mark scheme again

 

[nehaoscar]

PLZ help me with this! i am unable to questions of polymerisation this is may june 08 !

1. Break the bonds at the peptide linkage (at O=C---NH)
This will give H2NCH2CH2NH2 and HOOCCOOH. This is condensation since water was initially removed to form the polymer.

2. Break the ester bonds
This will give HOCH2CH(CH2CH3)COOH and HOCH2CH(CH3)COOH. This is condensation.

3. There are 3 different sub-parts so just break the bonds and add a double bond to the carbons that had the bonds
This will give CH2=CH-CH3 and CH2=CH-CONH2 and CH2=CH-C6H5(benzene ring). This is addition

 

[bakhita]

So what exactly do we have to study to prepare for Paper 4?
Does it include both AS and A2 concepts, or just A2 ones?

For example, do i need to just study A2 organic chemistry (Benzene etc.) or the entire AS organic chemistry as well?

For Paper 4, we needa revise the entire syllabus both AS and A2. Refer to page 10 of syllabus which, under Paper 4, states:
"...All questions will be based on the A Level syllabus but may require knowledge of material first encountered in the AS Level Syllabus..."

 

[nehaoscar]

So what exactly do we have to study to prepare for Paper 4?
Does it include both AS and A2 concepts, or just A2 ones?

For example, do i need to just study A2 organic chemistry (Benzene etc.) or the entire AS organic chemistry as well?

AS is required ... mainly the organic parts and also some knowledge from the group 2

 

[Aishayasin]

Can anyone tell me how to solve 9702/01/O/N/07 question 10