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AQA A Level Chemistry Paper 3 7405/3 - 23 Jun 2022 [Exam Chat]

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Guys for alkene A did u put but-1-ene
with part b being it has no chiral centre

And for isomer B and C did u put E and Z but-2-ene
with part b being there is restricted rotation around the C=C bond

yes, except I said for A that it was because the first C wasn't bonded to 2 different groups

Reply 1141

Zen02

Original post by Lilzz.x

just watching videos.. i've honestly given up, especially since my friends are all done </3

thats how im feeling about bio tmr i really cba rn

Reply 1142

coffeelover3

what did u guys put for that electrode question? it was like 'why does -- act as a catalyst in this reaction? refer to the electrode potentials in the table in your answer'

personally i put that -- (i dont remember what molecule) acts as a catalyst bc it reduces the -- to -- as it has a less positive E value for that reaction, then oxidises -- to -- as it has a more positive E value than that reaction

Reply 1143

Jameela9876

Original post by ayesha ayesha

how many marks was the temperature one where you had to work out wat temp it was feasible at. just realised I didn't divide S value by 1000

Couldn’t you just like times the h value by 1000?

Reply 1144

gryphon94

Original post by sunshine11111

guyssss u know the catalyst 6 marker
i was like what do i write for 6 marks
i didnt have much to say
like it only asked for definition and why and the eqautions
what didi u guys put

For that one i said that the autocatalysis is when one of the products acts as a catalyst and then that the reaction was slow at the start because the conc. of [M2+] was small and then after the reaction occurs more M2+ is being produced so the reaction rate increases and the colour of solution changes to pink . also i gave a graph with a curve to show the process of this reaction and an ionic equation of MnO4- and M2+ catalysing.

Reply 1145

gryphon94

For that one I said that (2Co2+)+(S2O8-)-->(2Co3+)+(2SO42-) and that (2Co3+)+(2I-)-->(2Co2+)+(I2) so basically it acts as a catalyst because it provides an alternative route with a lowe activation energy for the reaction because obvioulsy SO8- and 2I- are negatively charged so they will repel each oher which means they have high activation energy for the reaction to occur and this helps with the cobalt catalsyt.

Reply 1146

techwiz12345

am i the only one that found paper 2 so so hard oh gosh i needed an A :frown:

Reply 1147

PhysicsG

Original post by techwiz12345

am i the only one that found paper 2 so so hard oh gosh i needed an A :frown:

I found paper 2 quite good but I messed up paper 1 🫤

Reply 1148

CobblyWobbly

What questions were there about rates?

Reply 1149

Scoobydoo987

Original post by techwiz12345

am i the only one that found paper 2 so so hard oh gosh i needed an A :frown:

Dw u cant do anything now just leave it,I had one bad exam and its annoying me everyday but whats worrying gonna do about it.

Reply 1150

notwastingtime

Quick Question- So we have any information what will be happening to the grade boundaries.

Reply 1151

MoonCheese

I just did a Paper 3 Chemistry past paper and got 64/90 so can anyone please tell me what grade could this likely be for this year's boundary grades?

(edited 10 months ago)

Reply 1152

TypicalNerd

Original post by MoonCheese

I just did a Paper 3 Chemistry past paper and got 64/90 so can anyone please tell me what grade could this likely be for this year's boundary grades?

That’s roughly 71%, which I’d guess is probably an A.

Reply 1153

Adas1332

Original post by TypicalNerd

That’s roughly 71%, which I’d guess is probably an A.

bro why did u do a past paper u already got an A* in chem lol

Reply 1154

TypicalNerd

Original post by Adas1332

bro why did u do a past paper u already got an A* in chem lol

Where exactly did I say I did a past paper?

I think you may have misread my last message.

Reply 1155

TypicalNerd

Good luck all. The end is now in sight and your much deserved summer break is just round the corner.

Let us hope the last two years of hard work gives each and every one of you the excellent grades you deserve.