S2O3 2- + 2H+  S + So2 + h20
so2 is acidic
SO2 + H2O --> H2SO3
Sodium thiosulfate and hcl, water bath, range of temperatures, conical flask on top of a black cross stopwatch, time taken for cross to disappear, rate is 1/time. Plot 1/time against temperature, exponential shape due to Arhenius equation

H2SO4  H+ + HSO4-
HSO4- <-> H+ +so4 2-
Ka is 7.21x10^-3
Increased conc of so4 2-, so equilibrium shifts left, H+ decreases and ph Increases

Salt bridge
Allows movement of ions
Platinum
C; HCL/1 moldm3
D: hydrogen gas at 100kPa
E: solution of fe2+ and fe 3+ at 1 moldm3
2Fe3+ + H2 --> 2Fe2+ + 2H+

-0.013V (gradient)
303K
-0.80V

Nucleophilic addition
Racemic mixture
Planar C=O, Equal probability of nucleophilic attack from above and below the plane, racemate formed
Draw optical isomers of 2hydroxypropanenitrile (mirror images in 3D)
C.h2s04/ 600K
3 repeating units with trailing bonds

Fe + h2so4  feso4 +h2
MnO4-(aq) + 8H+(aq) + 5Fe2+ (aq) Mn2+ (aq) + 4H2O (l) + 5Fe3+ (aq)
Colourless to pale pink/purple
22.65 cm3
1.47% as two readings

Some multiple choice
-1139
+0.78V
Benzoic acid

Reply 23

haf4321

7

oh

got that wrong then- why is it benzoic acid

Original post by melonmelon

calcium sulfate and benzoic acid

Reply 24

Onisparks

10

What question is this? Lmao I've already forgotten it what was on the test.

Original post by haf4321

oh

got that wrong then- why is it benzoic acid

Reply 25

Dextro845

10

For standard solution
Step 1 - Weigh the sample and weighing boat/bottle and then weigh the weighing boat and work out the difference
Step 2 - Disolve in distilled water and use a glass rod to mix
Step 3 - Transfer to a 250cm^3 volumetric flask and invert

Reply 26

melonmelon

8

cant remember the other options, but 2017 paper 3 question 3 was about purification of benzoic acid solid from ethyl benzoate

Original post by haf4321

oh

got that wrong then- why is it benzoic acid

Reply 27

taceboll

4

some numbers i got to save:

104.5 for something and i hv no idea what
7.2 x10 ^-3 for Ka

-0.012 - gradient
301 - temp
-0.8 ? i dont rmbr but it was the same emf question

22.65cm^3?
and 1.47% for % error

and my MCQ
CADACBBABAAADABCBBABCDDDCCAACD (some r prolly rlly wrong lmfao)

(edited 4 years ago)

Reply 28

Onisparks

10

Oh ok thanks

Original post by melonmelon

cant remember the other options, but 2017 paper 3 question 3 was about purification of benzoic acid solid from ethyl benzoate

Reply 29

username4385726

12

Would 7.207*10^-3 get me 6 marks?

Reply 30

TomSR

11

Original post by ChemEng456

Would 7.207*10^-3 get me 6 marks?

Probably 5 because it said to 2 d.p.

Reply 31

username4385726

12

It asked 3.s.f, didn't it? :frown:

Reply 32

science_geeks

15

Original post by Ninja8004

For standard solution
Step 1 - Weigh the sample and weighing boat/bottle and then weigh the weighing boat and work out the difference
Step 2 - Disolve in distilled water and use a glass rod to mix
Step 3 - Transfer to a 250cm^3 volumetric flask and invert

Yes! I got that too :smile:

Reply 33

blueoreo

3

How did everyone find the exam? I thought it was alright but I’ve definitely made a few mistakes, idk why everyone is saying it was a blessing? Really worried I’m not going to get an A. :frown:

Reply 34

Qwertlkjh

3

I think most people won’t remember the letter they put for each question in the multiple choice. So can we start making a list of the actual answers in the multiple choice (doesn’t have to be in order) as that’s the thing people will actually recall

Reply 35

smaiu

11

I absolutely destroyed that exam.

Reply 36

Edexcel Are mugs

9

So 1.25*10^-3
100cm^3 at 1 mol
Mole fraction 0.352
0.408 for concentration
Just a frw

Original post by Qwertlkjh

I think most people won’t remember the letter they put for each question in the multiple choice. So can we start making a list of the actual answers in the multiple choice (doesn’t have to be in order) as that’s the thing people will actually recall