Edexcel A2 Chemistry 6ch04/05 JUNE 2015

Does anyone have a pdf revision guide? If yes, could you please share? :smile:

Reply 521

Ripper Phoenix

17

Original post by aersh8

Does anyone have a pdf revision guide? If yes, could you please share? :smile:

pdf rev guide for??

Reply 522

bbyturtlexox

12

Original post by Pilz

I got a question, why does the alkylation of benzene (Friedel-Crafts) need to take place in dry ether? Does water react with RCl? Does it react with the catalyst, AlCl3?

the AlCl3 is sensitive to hydrolysis so needs to be dry

Reply 523

Original post by Ripper Phoenix

pdf rev guide for??

Chemistry, units 4 and/or 5 :smile:

Reply 524

Ripper Phoenix

17

Original post by aersh8

Chemistry, units 4 and/or 5 :smile:

oh the official edexcel ones? I'm just saying that they aren't super useful.. i have them in hard copy

Reply 525

Original post by Ripper Phoenix

oh the official edexcel ones? I'm just saying that they aren't super useful.. i have them in hard copy

Any would be awesome - I feel I won't have time to read a whole textbook (I stupidly left chemistry for the very last minute) so a revision guide would be great. I used the edexcel one last year for AS and it worked out well, but I can't find one for A2 through Google.
The Philip Allan ones do seem better for the other subjects, so I guess it's the same case for chemistry but I can't find those either.

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Reply 526

Pilz

could someone explain this for me please?

The answer:

Spoiler

(edited 8 years ago)

Reply 527

cerlohee

16

Original post by Pilz

could someone explain this for me please?

The answer:

Spoiler

In the first step, hydroxide reacts in a substitution to form the alcohol, but also with the acid group to form a sodium salt. Adding a strong acid reforms the carboxylic acid group. It's the same thing as when you add a strong acid after base hydrolysis of an ester :smile:

Reply 528

Pilz

Original post by cerlohee

In the first step, hydroxide reacts in a substitution to form the alcohol, but also with the acid group to form a sodium salt. Adding a strong acid reforms the carboxylic acid group. It's the same thing as when you add a strong acid after base hydrolysis of an ester :smile:

ooooooooh I geddit

Reply 529

bluegreenjade

can someone tell me how the Answer is B please? Feel pretty stupid and panicking atm because I don't know how its B i thought it was A (June 2010 question 11 6CH04/01)

Which of the following has two singlet peaks in its nmr spectrum?
A. Methanal HCOH
B. Methanol CH3OH
C. Chloromethane CH3Cl
D. Dichloromethane CH2Cl2

Reply 530

MoHoosen9167

10

Has anyone been on the chemrevise Wordpress website? Their revision summaries are second to none, as well as their synthesis routes and transition metal summaries.

http://chemrevise.org/3-edexcel-revision-guides/

Someone asked for a PDF revision guide, these are better! Honestly I just discovered it last week and they're amazing

Reply 531

AnishaJayne

2

Original post by bluegreenjade

can someone tell me how the Answer is B please? Feel pretty stupid and panicking atm because I don't know how its B i thought it was A (June 2010 question 11 6CH04/01)

Which of the following has two singlet peaks in its nmr spectrum?
A. Methanal HCOH
B. Methanol CH3OH
C. Chloromethane CH3Cl
D. Dichloromethane CH2Cl2

Methanol is an alcohol, so it's got 2 different hydrogen environments which will both split into 2 singlets. As one H is joint to the O and the other 3 are on the carbon. Both are not bonded to adjacent carbons with hydrogens on. So it has to be B

It can't be A as both the hydrogens are in the same environment, producing just one singlet peak! Hope this helps

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Reply 532

Raghadabuali

2

Original post by bluegreenjade

can someone tell me how the Answer is B please? Feel pretty stupid and panicking atm because I don't know how its B i thought it was A (June 2010 question 11 6CH04/01)

Which of the following has two singlet peaks in its nmr spectrum?
A. Methanal HCOH
B. Methanol CH3OH
C. Chloromethane CH3Cl
D. Dichloromethane CH2Cl2

the ans is B
the first environment is H on the Ch3 and ite singlet and the second environment is the H in tge OH also singlet
it cannot be A because methanal will only have one peak since it is symmetric

Reply 533

Original post by MoHoosen9167

Has anyone been on the chemrevise Wordpress website? Their revision summaries are second to none, as well as their synthesis routes and transition metal summaries.

http://chemrevise.org/3-edexcel-revision-guides/

Someone asked for a PDF revision guide, these are better! Honestly I just discovered it last week and they're amazing

Yeah I used those throughout the year thinking they were perfect, but I found out in the mocks that they lack essential detail on some topics

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Thanks!

Getting very confused with the chemrevise notes on entropy. Am I correct in saying that a decrease in entropy will cause an deltaS system to be positive because energy is being transferred from the surroundings to the system (therefore less ways of arranging energy quanta and decreased entropy)?? In the chemrevise notes it says 'if the reaction involves a decrease in entropy (deltaS system is negative)'. Are these notes incorrect or is it just me being stupid :confused:

(edited 8 years ago)

Reply 536

rasil23

3

Original post by SM2468

Getting very confused with the chemrevise notes on entropy. Am I correct in saying that a decrease in entropy will cause an deltaS system to be positive because energy is being transferred from the surroundings to the system (therefore less ways of arranging energy quanta and decreased entropy)?? In the chemrevise notes it says 'if the reaction involves a decrease in entropy (deltaS system is negative)'. Are these notes incorrect or is it just me being stupid :confused:

increase in entropy - more disorder therefore delta S system is +ve
Decrease in entropy - less disorder, therefore delta S system is -ve
Entropy is the measure of disorder in a system

Reply 537

SM2468

ImageUploadedByStudent Room1433768037.204024.jpg32.0KB

Original post by rasil23

increase in entropy - more disorder therefore delta S system is +ve
Decrease in entropy - less disorder, therefore delta S system is -ve
Entropy is the measure of disorder in a system

Yup just be being stupid then hahah. Thank you!!

Reply 538

AnishaJayne

2

Is anyone able to explain this please?iv

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Reply 539

bluegreenjade