Edexcel IAL WCH04 ~ 13th Jan 2014 ~ Unit 4

Relaxedexams

2

This thread is for discussions for the upcoming Edexcel International A levels in January 2014 for chemistry unit 4.

Hi there,

While you're waiting for an answer, did you know we have 300,000 study resources that could answer your question in TSR's Learn together section?

We have everything from Teacher Marked Essays to Mindmaps and Quizzes to help you with your work. Take a look around.

If you're stuck on how to get started, try creating some resources. It's free to do and can help breakdown tough topics into manageable chunks. Get creating now.

Thanks!

Not sure what all of this is about? Head here to find out more.

Reply 2

Relaxedexams

OP

2

Hey guys, the thread has been quiet...
The exam is about a month away, anyone here doing Chemistry IAL this Jan?

Reply 3

kcapsoccer

1

Hi

I am doing chemistry IAL and i am writing unit 4, unit 5 and unit 6b. Which ones are you taking?

Posted from TSR Mobile

Reply 4

Relaxedexams

OP

2

Original post by kcapsoccer

Hi

I am doing chemistry IAL and i am writing unit 4, unit 5 and unit 6b. Which ones are you taking?

Posted from TSR Mobile

Hey,

I'm doing unit 4 chem, phy and bio.

Reply 5

kcapsoccer

1

Original post by Relaxedexams

Hey,

I'm doing unit 4 chem, phy and bio.

ohh nice! what topic are you finding the hardest in chem unit 4? i think that spectroscopy is the hardest one. :/

Posted from TSR Mobile

Reply 6

Relaxedexams

OP

2

Original post by kcapsoccer

ohh nice! what topic are you finding the hardest in chem unit 4? i think that spectroscopy is the hardest one. :/

Posted from TSR Mobile

I find organic chemistry to be rather annoying :P

Reply 7

DevilSmite

yea spectroscopy and chromatography are a major pain in the conicals (the apparatus) , esp the environment/nmr bit :/

Reply 8

RoyalBlue7

19

Good luck for anyone doing it today

Posted from TSR Mobile

Reply 9

kcapsoccer

1

you too lets hope we will all end up with good results! :smile:

Reply 10

TheKingOfTSR

13

Hi.

For that section C sucrose question..they've said to comment on the effect on the extent of the reaction if temperature is increased.
But my problem is that this reaction is not reversible, hence if it does take place it would go to completion right? So there would be no effect on the extent of the reaction? :dontknow:

Posted from TSR Mobile

Reply 11

RoyalBlue7

19

Original post by TheKingOfTSR

Hi.

For that section C sucrose question..they've said to comment on the effect on the extent of the reaction if temperature is increased.
But my problem is that this reaction is not reversible, hence if it does take place it would go to completion right? So there would be no effect on the extent of the reaction? :dontknow:

Posted from TSR Mobile

Yes, don't see where the mark lies.

The titration graph was misleading imo, because even after adding 30cc of HCl the pH would still be higher than zero (by calculation). Why then did they extend the graph to negative pH and why ask the previous question??

Reply 12

Labib

the pH of 4 mol/dm3 of acid was about -0.6. So at the 30cc the pH of the soln would be -0.6
The curve would touch the -0.6 pH mark at 30 cc

Reply 13

Labib

Would be glad if any one has the unofficial mark scheme or question paper for unit 4.
And best
of luck for unit 6

Reply 14

Labib

Original post by TheKingOfTSR

Hi.

For that section C sucrose question..they've said to comment on the effect on the extent of the reaction if temperature is increased.
But my problem is that this reaction is not reversible, hence if it does take place it would go to completion right? So there would be no effect on the extent of the reaction? :dontknow:

Posted from TSR Mobile

I don't think the question was like that! I forgot the actual question. If you can tell me the actual question then maybe I can give you an answer.

Reply 15

RoyalBlue7

19

Original post by Labib

the pH of 4 mol/dm3 of acid was about -0.6. So at the 30cc the pH of the soln would be -0.6
The curve would touch the -0.6 pH mark at 30 cc

I don't think so.

The number of excess mol of H ions at 30cc= 0.005 * 4 = 0.0020

Therefore concentration of H ions = 0.020/0.055 = 0.3636363636

pH at this point= 0.439

So I guess it shouldn't be at -0.6 but should appear to approach it at that point

Reply 16

TheKingOfTSR

13

Original post by Labib

the pH of 4 mol/dm3 of acid was about -0.6. So at the 30cc the pH of the soln would be -0.6
The curve would touch the -0.6 pH mark at 30 cc

No.

pH of the solution is above that as only 5cc of acid is present in 55cc of solution.

I guess as long as your graph isn't horizontal at the end and it ends above -0.6 then you'll get the mark.

Posted from TSR Mobile

(edited 10 years ago)

Reply 17

TheKingOfTSR

13

Original post by Labib

I don't think the question was like that! I forgot the actual question. If you can tell me the actual question then maybe I can give you an answer.

Explain the effect, if any, of increasing the temperature on the system entropy change, the total entropy change and the extent of the reaction. (4)
^something worded like that.

The combustion of sucrose isn't reversible, so how come "extent of the reaction "?
If the reaction does take place, (kinetic inertness is overcomed) then it would go to completion right?

Edit: not system but surrounding entropy change. :biggrin:

Posted from TSR Mobile

(edited 10 years ago)

Reply 18

examman123

It was the surrounding entropy change and total entropy change..

When temperature is increased obviously surrounding entropy change will decrease (because entropy change of surrounding = -deltaH/T)
Since total entropy change = entropy change of surrounding + entropy change of system.. the value for total entropy change will decrease as well..
however, the reaction will undergo completion as it's an exothermic reaction (so, despite what temperature the surrounding is positive) and the entropy change of system is also positive as disorderedness increases as products are formed...

Reply 19

kcapsoccer

1

Original post by examman123

It was the surrounding entropy change and total entropy change..

When temperature is increased obviously surrounding entropy change will decrease (because entropy change of surrounding = -deltaH/T)
Since total entropy change = entropy change of surrounding + entropy change of system.. the value for total entropy change will decrease as well..
however, the reaction will undergo completion as it's an exothermic reaction (so, despite what temperature the surrounding is positive) and the entropy change of system is also positive as disorderedness increases as products are formed...

do you remember how many marks did that question have?

Posted from TSR Mobile

Edexcel IAL WCH04 ~ 13th Jan 2014 ~ Unit 4

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you