The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Edexcel A2 Chemistry 6ch04/05 JUNE 2015

Scroll to see replies

Original post by economicsrocks
I'm kicking myself about the ph of water, because I knew the answer but I doubted myself and wrote the wrong thing! It was actually that as the ratio of H+ and OH- ions remain the same, the pH is still 7 so it is still neutral and the student is correct.

For the jelly, I put it enhances the taste, and it makes it seem slightly tangy or sour. I literally had no idea haha.

What did you put?


As temperature increase the ph decreases because the h ion conc increases. It still remains neutral though. Neutral doesn't equal ph7

Posted from TSR Mobile
Original post by Wahid1
Acid chloride and esterifocation.

Did they specify 2sf??? I wrote 3.06 tonnes ****


Posted from TSR Mobile

They did :/ I realised and changed it at the last second
Reply 1182
Avatar for Evi333
Evi333
I said that for the anomaly question that temperature could have caused it because an increase in temp increases the amount of successful collisions... is this right?
Original post by Callum_Stewart
They did :/ I realised and changed it at the last second


**** i think i got 3.2
Original post by cbfks
Advantages and disadvantages of the 2 processes:

Palm oil:
+: Green as carbon neutral
-: Oil obtained from food sources is unethical
Coffee:
+: ?
-: Used methanol which is obtained from unsustainable crude oil


+ of coffee could be that it uses the coffee grounds and therefore reuses materials?
Original post by asdfghnmbmn
There goes my uni place... Ffs


:frown: i feel you. praying for low grade boundaries
Original post by _bindra
I wrote that at higher temperatures a greater proportion of H20 dissociates into H+ and OH- (described using the Entropy of surroundings and RlnK). This leads a greater concentration of H+ and therefore the pH is not 7. Student is incorrect. However the solution still remains neutral due to equal amount of H+ and OH- produced.


Oh I put that! I didn't mention that the solution remains neutral, but I did say the equilibrium restores itself. Do you think that's right?
Original post by economicsrocks
I'm kicking myself about the ph of water, because I knew the answer but I doubted myself and wrote the wrong thing! It was actually that as the ratio of H+ and OH- ions remain the same, the pH is still 7 so it is still neutral and the student is correct.

For the jelly, I put it enhances the taste, and it makes it seem slightly tangy or sour. I literally had no idea haha.

What did you put?


I thought as temp increases ph gets lower bc its endothermic
Original post by Amanda Brown
The titratration curve questions--> what three points did u put for the ph being above 7?


At complete neutralisation, lots of CH3CH2COO- is produced.
This is a weak base which can react with water

CH3CH2COO- + H2O --> CH3CH2COOH + OH-

It's weird but basically the conjugate base adds OH- to the solution increasing the pH.
i crossed out sodium hydroxide for biodiesel and wrote something else, will i get marked correct?
Original post by Undisclosed 15
As temperature increase the ph decreases because the h ion conc increases. It still remains neutral though. Neutral doesn't equal ph7

Posted from TSR Mobile


Oh in which case I should be ok. I didn't say it still remains neutral and I did say water dissociates into more H+ ions. Thanks haha :smile:
I still don't believe that (x) was first order!!!

Only me and another person in my class got Second order for X
Original post by Connor_1949
At complete neutralisation, lots of CH3CH2COO- is produced.
This is a weak base which can react with water

CH3CH2COO- + H2O --> CH3CH2COOH + OH-

It's weird but basically the conjugate base adds OH- to the solution increasing the pH.


Would you get a mark or 2 for saying one is a weak acid and the koh is strong base?

So more oh- compared to h+?


Posted from TSR Mobile
Original post by baymax96
I thought as temp increases ph gets lower bc its endothermic


That's what I put in the exam, so yeah hopefully this is right! :smile:
Original post by economicsrocks
Oh I put that! I didn't mention that the solution remains neutral, but I did say the equilibrium restores itself. Do you think that's right?


I hope so, check old markschemes they usually give a mark for mentioning something that sounds like LeChateliers principle. As for the neutral bit, the question didnt ask anything about neutrality but I included it anyway. It only asked about its pH.
that was thoroughly enjoyable, if by enjoyable I mean vomit inducing.

convincing myself it was definately not a buffer on the first question was when it started to go down hill. Then deciding that catalysts should not be in the rate equation.

section C and A are okay though
I just have a terrible habit of getting the correct answer and changing it to the wrong one.
For everyone confused about the reaction in step three: http://wwwchem.csustan.edu/consumer/aspirincons/aspirincons.htm
It WAS esterification, they use acetic anhydride, which is the industrial way of adding an acyl group on, which is an esterification reaction.
Original post by Wahid1
Would you get a mark or 2 for saying one is a weak acid and the koh is strong base?

So more oh- compared to h+?


Posted from TSR Mobile


Hopefully!
The only respectable section was section C


Posted from TSR Mobile
Original post by Callum_Stewart
It was esterification, you could have used ethanoyl chloride or ethanol. I said ethanol.


Wasnt it ethanoic acid cus the alcohol group was on the benzene (cant remember exactly what it was)


Posted from TSR Mobile

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you