Hard as hell

Difficult

Alright

Easy

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Question

Marks

Answer

Additional Comments

Yo btw if u guys could add qs here and the answers that would be helpful thx

No

Give the formula for enthalpy of solution of KOH inc. state symbols

1

KOH(s) -> OH-(aq) + K+(aq)

Work out the volume of the solution used in the experiment working out deltaH soln of KOH vs

5

53.4cm3

Why was it that unit btw - because it said density = 1g/cm^cm^3 so the mass and volume equal so m in q=mcT was cm^3

Enthalpy of solution question

2

-61

Was it 2 or 3 marks? It was 2 ohh okay,

Why is data book value of deltaH soln different to the one calculated from the experiment?

1

heat loss to surroundings or incomplete reaction (ms accepts both!)

Not purely ionic has some covalent character

not heat loss to environment the question is on enthalpy of solution, so must be incomplete dissolution/incomplete dissolving of KOH.

Variables kept the same for iodine prac

3

Volume of starch

Person keeping track of time

Temp

Size  is of container?

Can someone verify this

Yes it’s right

Total volume of reaction mixture should be constant?

What about temp?

Hi ^ regarding your enquiry, yes Temp is correct you want to keep that constant as we’re only Varying CONCENTRATION (by manipulating volume in each resulting mixture)

Total volume of reaction mixture is creditworthy

Volume of starch is correct because we dont want to change that when measuring the concentrations in respect to the other reactants.

Work out the order of reaction of [H+], [I-] and [H2O2] in the iodine clock reaction, and explain how you worked out the order of [I-]

3

1

1

0

[I-] is first order because it increases by a factor of 2, time decreases by a factor of 2 = conc proportional to time

Nah bro that’s not what ur meant to do

calculate the percentage uncertainty

2

2.5%

(Add the two uncertainties together / by 20 X 100)

It said uncertainty for experiment 3

So 0.01 + 0.01 divided by 20 and multiplied by 100.

Kc value

6

Either :

-49  (6/6) I thought it was 45.9

- or 56.25(4/6) error carried forward failed to take into account 2xFe

- 562500- probably 3 failed to convert

Nah 2 as u don’t convert bro

I got 562.5 lol

Same i dont get why its 45.9

Potentially an ECF for 562.5

Its 45.9 (or 40smth) because firstly u had to take into account that is was Fe2(SO4)3 so multiply moles of that by 2 to get moles of Fe. Secondly u gotta divide ur eq moles by the volume (0.1dm3)

Its only 45.9 idk where -49 is coming from lol

Everyone I have spoken to has gotten a different answer icel.

Can some just do the full the thing and upload a screenshot of it here with the working out

Rate equation

1

rate = K [H2O2][I-]

Why is the uncertainty of the stopwatch greater than the smallest division?

1

Reaction time // human error

Colour change subjective? No because it occurs instantly

I think the answer is because you take 5 experimental measures and do it twice for each experiment ( start and end)

how to reduce uncertainty?

2

1- increase conc,

2-  so it increases the time (not sure about 2nd m

ark)

Sigh could saying “carry out at a lower temperature” count cause it still increases the time? (I put that too)

What about increasing volume ?

Three errors with the cell set up to measure the emf of an Fe2+/Fe3+ cell and changes to make it correctto3

3

1 moldm-3 H2SO4-needs to be o.5moldm-3 or 1moldm-3 of a monoprotic acid (HCl)

Fe electrode- needs to be a Pt electrode

NaOH as the salt in the salt bridge- needs to be an inert salt like KNO3

Voltmeter not correct place

Iron filings are added to copper (ii) sulfate, the solution goes green then a brown ppt forms. Explain the reaction using electrode potentials, give a formula for the overall reaction, give the cell notation for if the overall reaction is was a cell, and the emf of the cell

6 RT

I ended up with an emf of 0.01, but I honestly have no idea.

I got 0.78 for EMf

0.78 EMF

Colour change from blue to pale green solution due to change from Cu(H20)62+ to Fe(H20)62+ and brown ppt due to formation of copper solid init, yeah but this aint on the spec that cu is brown

this ms for 6 marks ?? conventional needed, ionic equation and why colour change occurs

1.11V? Yess i did the 2 Copper equations and the Fe but it seems it was just the copper equation inbetween which i dont get

Which two equations did we need to do, because i picked the top 2

Regarding the above enquiry, it was 1 and 3

Why was the mixture quenched with water

2

To sto it p the reaction with dilution.

Smth about equilibrium

MCQ - Which of the following features makes the voltmeter able to measure voltage of a cell or smth

1

high resistance (last option)

A procedure is outlined to distinguish between propan-1-ol and

propan-2-ol (oxidation).

State the oxidising agent used. Give details on how to carry out the procedure, describe a test tube reaction that would tell the products of oxidation apart, and describe how to use IR to tell the products apart.

6

oxidising agent: acidified potassium dichromate

CH3CH2CH2OH + [O] —> CH3CH2CHO + H2O (aldehyde formed)

CH3CHOHCH3 + [O] —> CH3COCH3 + H2O (ketone formed)

test: tollens reagent, silver mirror formed or fehlings solution, brick red ppt for aldehyde. NVC FOR KETONE

same peaks C=O, C-C, C-H so to further identify, use the fingerprint region below 1500cm-1 and compare results to a known data book value

Isnt it IR for original solution？yes

FOK I FORGOT FINGERPRINT REGION

Why no carboxylic acid formed

Cus it wasnt under reflux. It was frac distillation

Cant u do reflux on both, and test COOH formed using sodium carbonate and nvc with propanone

I only mentioned the same peak shows for C=O and then fingerprints differ, would that be sufficient for like the tier 3 part do we think?

Further oxidation conditions to produce carboxylic acid

1

Heat under reflux

FUK

Reflux practical set up drawing

2

Just some additional guidance here, ensure there are no gaps in your apparatus and that the top IS NOT sealed, which could deduct a potential marking point.

Why is anti bumping granules used

1

Prevent large bubbles/produce smaller bubbles/ prevent vigorous boiling

would prevent splasback into the

Type of isomerism

1

Some say optical some say geometric isomerism

It wasn't optical I put E/z

It was geometric

Positional?

use of the ester

1

Biodiesel

Biodiesel is the only correct option because it is a methyl ester

It wasn’t just any ester, it was the methyl ester formed by chain B. And biodiesel is a mixture of methyl esters

Biodiesel is literally made from reacting vegetable oils with methanol. Isnt it the carboxylic acid with methanol

It literally said in the question that this was from rapeseed oil (which I'm guessing is a vegetable oil)

It is a vegetable oil.

Number of Carbons

2 marks

It was 10 and 4 i think

I put 9 and 4/2

Which one is 8?

The carbon ester thingy

What about the number of isomers?

I wasnt sure ngl

Calm

What do you think about this paper

It was definitely better than 2, but they gotta still lower gb, i thought it was ass icl,

I flopped paper 2 and the emf question today

12

I got 8 me too

I got 8 too

I thought paper 2 went better for me than paper 3.

I cannot lie i cant remember what i put for these mcqs lol

I pray A* is like 74 or sm

F  hi or this paper’?

Generally  %

• Paper 3 grade boundaries for 2024 paper was 70/90
• I do think this years paper 3 was a bit harder ?
• Noooo i think it was more accessible than 2
• The paper 3?? 100% only q i hated was the electro
• Tbh i didnt mind the long choice questions. I It was the mcq i think i lost like 10 marks on mcq
• Was this timing or like knowledge
• Probs timing.
• Alot of ppl r in that
• boat tbh
• Paper 2 went better for me. Then paper 1. Then paper 3
• ??? oh paper 2 was atrocious i single handedly lost an A* coz of that
• Ah i mean this paper was mid. Idk if i did good or bad. Half of the mcq questions are missing
• Doesnt help in which option i picked too

i got carbon 9 and 4 isomers

MCQ - uranium

1

Answer: 19

Isn't it radium

No that’s a diff Q for p sub shell

Yeah bro

MCQ - what  element is in P block?

1

RADON

NOT radium as Radium is in the S block (left hand side of periodic table)

MCQ - dipeptide thing

1

C

MCQ - Which complex produces an octahedral complex MCQ

1

Cobalt one

MCQ - % Abundance of 235UF6

1

19

MCQ - which are the correct structures? (The one where we had to correct SiO3)

1

A - SiO2 giant covalent all the metals formed ionic and p4o10 and SO2 was simple molecular

MCQ - Decreasing order in pH

1

Na, Mg, Cl

This is correct, remember that Sodium is more soluble than magnesium, so sodium will have the highest pH of the 3!

MCQ - What is the shape of tollens reagent and formula

1

A - Linear Ag(nh3)2

MCQ - which one has a tetrahedral structure?

1

FeCl4-

MCQ - structure of Transplatin

1

B

Swear it was cisplatin which was

nah bro idts

Ensure that the option you picked did NOT have the CL LIGANDS ON SAME SIDE!

MCQ - Compound Y is converted to X via dehydration

1

Propene - C

MCQ - shape of P4O10 and H3PO4 thing

1

tetrahedral then pyramidal (in that order)

MCQ - fermentation

1

anaerobic respiration and fractional distillation

No it's anaerobic respiration and filteration -

It isnt filtration, filtration is a process involved but it’s actually filtered to remove yeast itself and NOT ethanol which was what the mcq wanted

MCQ - Which statement is true,

Alkene is made from thermal

SO3 is made

 from combustion

1

A

MCQ - which one shows OH- not acting as a base?

1

D (the C-Br one)

MCQ - which one is a function of an enzyme?

1

polymer

MCQ - what are the observations when Strontium is added to water?

1

colourless solution AND effervescence

MCQ - covalent bond and hydrogen bonding

1

it was either V and W OR V and U honestly a 50/50😭😭😭B

can’t remember the order but anyway it should be one with S-H and one with any of the hydrogen bond

It is definitely C for that question because you might form ionic bond for NH3+and COO- if you choose D. Therefore only C is right. (I got that question wrong as well)

MCQ - Electrophilic addition of cyclic compound (last Q)

1

I thought it was A because B is the minor product. For A there is a carbocation rearrangement.

B