It was an reasonable paper, but I know I've made some silly mistakes already... There were some multiple choice questions were really trying to trick you.

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Reply 348

87Mack

Original post by JohnMcButts

There were 2 moles

2SO2 + O2 -> 2SO3

it only had 1 mole in the equation given tho

Reply 349

Studentet

Original post by Barklimus

Pretty that the reagent for turning the the alkene into the blank product (C4H8Br2) was Br2. Then, to turn that into a diol, you could use NaOH.

I put that too but Cl2 instead of Br2!

Reply 350

snickercell

Original post by A Sajid

Low temperatures push the reaction to the exothermic side. And the forward reaction/ product had less molecules than the reactants. So increase in pressure pushed the equilibrium to the product side. And then you talk about how high pressure costly blah blah.

But if low temp and high pressure push the equilibrium to the product/right hand side then surely that wouldn't produce a good percentage yield since more of the product would break down to form reactants?? There was a similar question in one of the specimen depth papers which is had a contradictory answer to the question in today's paper?

Original post by Jitesh

Certainly but not sure how many with it being a new spec and all

Ahh ok that's alright then, hopefully won't lose too many marks

Reply 351

Clintbarton

Original post by Studentet

I put that too but Cl2 instead of Br2!

Same thing because they're both halogenation?

Reply 352

Harryg123456

Original post by Barklimus

AHCK You needed to square root it, cos that value is (SO3) squared. I got about 0.876moldm-3.

Yep that's what I got as well

Reply 353

Jitesh

Original post by Studentet

I put that too but Cl2 instead of Br2!

That's fine it would be alright for any suitable reagent
Br2 would just show a clearer colour change and is normally used in experiments so it would probably be more common for people to put that

Reply 354

11234

Original post by Jitesh

It's a bit blurry but the top circle on the Oxygen I drew as a different symbol but I was not sure if it meant different as in a circle when uses crosses to represent it??

I used it for the dative one. What did they mean?

Reply 355

87Mack

Original post by A Sajid

Lmao what kind of science has this don been doing. Its like saying you have to cube 02 :biggrin:

im a don now is it? nah but seriously tho wasnt it only one mole ?? if its not i got that wrong then.

Reply 356

S.G.

Original post by snickercell

Did they?? Dang it! Would i still get some marks for correct working out albeit with wrong numbers?

I'm not sure as that was the first step. You might get 1 for method

Reply 357

Clintbarton

Original post by 87Mack

concentration of S03 = 0.768 anyone????????

I think I got something like that.

Reply 358

h3rmit

Original post by Barklimus

AHCK You needed to square root it, cos that value is (SO3) squared. I got about 0.876moldm-3.

I got this

Original post by 87Mack

nah why do you square it? there was only one mole of SO3

You have to look at the stoichiometry

Original post by Clintbarton

That one messed me up and I ran out of time at the end to finish working out, I think i put A because B (or C) wasn't even E/Z.

They were all E/Z, even the ones with the chloros not on the double bonding carbons had hydrogen and methyls on the double bonding carbons (so two different atoms/groups of atoms)

Original post by tamoni4

Yes, exactly. Since there were 2 measurment, you had to double the error and then divide by the mass of water and multiply by 100.

Lol I forgot to double the %error, gg me

Reply 359

Firenze26

... I really don't know whether to be happy that the exam was relatively decent or scared by the fact that this will usually mean a high grade boundary.

Btw, do you guys know what reagent was used to add that oxygen in the second stage of prep in that last question?

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