Edexcel A2 Chemistry 6ch04/05 JUNE 2015 Watch

Undisclosed 15
Badges: 17
Rep:
?
#1181
Report 3 years ago
#1181
(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
0
quote
reply
Callum_Stewart
Badges: 1
Rep:
?
#1182
Report 3 years ago
#1182
(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
0
quote
reply
Evi333
Badges: 0
Rep:
?
#1183
Report 3 years ago
#1183
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?
0
quote
reply
goonieskellie
Badges: 2
Rep:
?
#1184
Report 3 years ago
#1184
(Original post by Callum_Stewart)
They did :/ I realised and changed it at the last second
**** i think i got 3.2
0
quote
reply
_bindra
Badges: 2
Rep:
?
#1185
Report 3 years ago
#1185
(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?
0
quote
reply
daisychain_
Badges: 13
Rep:
?
#1186
Report 3 years ago
#1186
(Original post by asdfghnmbmn)
There goes my uni place... Ffs
i feel you. praying for low grade boundaries
1
quote
reply
economicsrocks
Badges: 3
Rep:
?
#1187
Report 3 years ago
#1187
(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?
0
quote
reply
baymax96
Badges: 2
Rep:
?
#1188
Report 3 years ago
#1188
(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
0
quote
reply
Connor_1949
Badges: 1
Rep:
?
#1189
Report 3 years ago
#1189
(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.
1
quote
reply
Mufinator
Badges: 1
Rep:
?
#1190
Report 3 years ago
#1190
i crossed out sodium hydroxide for biodiesel and wrote something else, will i get marked correct?
0
quote
reply
economicsrocks
Badges: 3
Rep:
?
#1191
Report 3 years ago
#1191
(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
0
quote
reply
Samuel745
Badges: 1
Rep:
?
#1192
Report 3 years ago
#1192
I still don't believe that (x) was first order!!!

Only me and another person in my class got Second order for X
0
quote
reply
Wahid1
Badges: 2
Rep:
?
#1193
Report 3 years ago
#1193
(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
0
quote
reply
economicsrocks
Badges: 3
Rep:
?
#1194
Report 3 years ago
#1194
(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!
0
quote
reply
_bindra
Badges: 2
Rep:
?
#1195
Report 3 years ago
#1195
(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.
0
quote
reply
bballislife
Badges: 1
Rep:
?
#1196
Report 3 years ago
#1196
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.
2
quote
reply
Callum_Stewart
Badges: 1
Rep:
?
#1197
Report 3 years ago
#1197
For everyone confused about the reaction in step three: http://wwwchem.csustan.edu/consumer/...spirincons.htm
It WAS esterification, they use acetic anhydride, which is the industrial way of adding an acyl group on, which is an esterification reaction.
0
quote
reply
Connor_1949
Badges: 1
Rep:
?
#1198
Report 3 years ago
#1198
(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!
0
quote
reply
Wahid1
Badges: 2
Rep:
?
#1199
Report 3 years ago
#1199
The only respectable section was section C


Posted from TSR Mobile
0
quote
reply
MeeraP07
Badges: 7
Rep:
?
#1200
Report 3 years ago
#1200
(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
0
quote
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of East Anglia
    UEA Mini Open Day Undergraduate
    Fri, 4 Jan '19
  • University of Lincoln
    Mini Open Day at the Brayford Campus Undergraduate
    Mon, 7 Jan '19
  • Bournemouth University
    Undergraduate Mini Open Day Undergraduate
    Wed, 9 Jan '19

Did you get less than your required grades and still get into university?

Yes (63)
29.44%
No - I got the required grades (122)
57.01%
No - I missed the required grades and didn't get in (29)
13.55%

Watched Threads

View All