Competition - post a photo you've taken of nature >>

AQA Chemistry Unit 2 (resit) CHEM2 10th June

Scroll to see replies

Reply 180

m3gangrace

Could you write about a squeaky pop with hydrogen for an observation? :/

Reply 181

username1194172

Original post by mgill17

What was the Termination step for the first Free Radical Substitution? You had to make something specific (I think it was C2H2Cl4??)

I think I put 2 *CHCl2 --> CHCl2CHCl2, its empirical formula had to be C2H2Cl4

Posted from TSR Mobile

Reply 182

mbh16

Original post by r p

what did ppl out for the 2 environmental and 1 economic advantage of using low grade ore?? I put:
Environmental: no SO2 released - no acid rain
Less energy required, less fossil fuels burnt
Economic: scrap iron is cheap

Do you think that's ok?

yeah i put the same as that for the first two but i think i put it costs a lot to provide energy to roast an ore

Reply 183

iiPablo

Original post by Sam Webb

Did you have to make it negative because it was exothermic?

It was asking about bond enthalpy, so the value of c-c would have been positive

Reply 184

Randomer98

Is it white solid or white ppt
It can't be ppt can it when it wasn't in solution?

Reply 185

mgill17

Original post by WhoDaresWins

1 mark for the white ppt, but can't believe this, found it so nice and then these silly mistakes just accumulated!
Grade boundaries will be sky high too.

Yeah, like it's never outright getting answers wrong, it's just forgetting little things or not using common sense then being like "Ahhh yeah I see that now" afterwards:/

Reply 186

mbh16

Original post by RME11

Great paper - The only real curveball was the method of rate of hydrolysis questions which was a HSW question.

Think I've got about 95ish there, only time will tell though!

I said use a piece of card with a black cross on underneath the beakers with the reactions going on and then time how long it takes before you can't see the black cross

Reply 187

ahsan_ijaz

Original post by WhoDaresWins

Oh fk thought it was elimination damn ittttt!!!
Also thought the didn't we have to name the alcohols?

Hi no

It was dehydration - which is same as elimination but re agent here is conc h2so4

Posted from TSR Mobile

Reply 188

mbh16

Original post by lahigueraxxx

What did people put for the role of H2SO4 in the reaction with sodium iodide?? I put oxidising agent, but it was a really badly worded question..

I think i put oxidising agent aswell

Reply 189

mgill17

Original post by Louisss

I think I put 2 *CHCl2 --> CHCl2CHCl2, its empirical formula had to be C2H2Cl4

Posted from TSR Mobile

I think/hope I got something with that empirical formula but it threw me off, it just seemed odd compared to the previous FRS questions?
Thanks!

Reply 190

username1194172

Original post by mgill17

I think/hope I got something with that empirical formula but it threw me off, it just seemed odd compared to the previous FRS questions?
Thanks!

Yeah I agree, I think it's because the equation that we wrote at the beginning wasn't the one used for the frs mechanism

Posted from TSR Mobile

Reply 191

username2280751

Original post by mbh16

I said use a piece of card with a black cross on underneath the beakers with the reactions going on and then time how long it takes before you can't see the black cross

I just said measure time taken for ppt to be formed - use equal volumes/concs, repeat test a few times to get a mean value etc. Probably dropped a couple of marks, but I can live with that.

Reply 192

mbh16

Original post by Seclusion

Magnesium produces the Bright white flame, not sure if they would credit white ppt, the second reason has to be about hydrogen, which is the pop.

yeah but doesn't it produce MgO which is a white solid?

Reply 193

iiPablo

Original post by mgill17

What was the Termination step for the first Free Radical Substitution? You had to make something specific (I think it was C2H2Cl4??)

Propagation step gave CHCl2• (CH2Cl2 + Cl• ---> CHCl2• + HCl), so termination step to give C2H2Cl4 was CHCl2• + CHCl2• ---> C2H2Cl4

Reply 194

mbh16

Original post by RME11

I just said measure time taken for ppt to be formed - use equal volumes/concs, repeat test a few times to get a mean value etc. Probably dropped a couple of marks, but I can live with that.

haha i completely forgot to say use the same concs/volumes but i said put in the reactants at the same time

Reply 195

ahsan_ijaz

The distillation Q

- one was aldehyde - one was COOH

COOH has hydrogen bonds which is stronger than vDw in aldehyde - it will allow vdw I'm sure

- infrared Q on why the spectra shows it's not that product
- u had to specify missing c=o bond and missing O-H bond

Mechanism - propene with h2so4 - electrophillic addition with a secondary carbocation formed

Explain why propan-2-ol is the major product (7)

Reaction proceeds through carbocations - so secondary is more stable than tertiary

State conditions for the two reactions and mechanism and state the role of oh- in both reactions :frown:

8)

Elimination - base
NS- nucleophillic

Elimination - NS
Re agent - KOH
Conditions - hot ethanolic solvent
NS - reagent - Naoh
Condition - water as solvent - warm aquoes

Mechanism was elimination

These 2 Q were the big 7 8 markers

Posted from TSR Mobile

Reply 196

mgill17

Original post by iiPablo

Propagation step gave CHCl2• (CH2Cl2 + Cl• ---> CHCl2• + HCl), so termination step to give C2H2Cl4 was CHCl2• + CHCl2• ---> C2H2Cl4

I definitely got that propagation step, but I can't remember for the life of me if I put that termination....I hope I did :frown:

Reply 197

mbh16

Original post by ahsan_ijaz

is that for the one where you had to say what the functional group was of T and S was?

Reply 198

ahsan_ijaz

Btw the ms - like some Qs will have more than one answers - eg for copper one you can write less energy requirement / the fact it's scrap iron it's cheap and plenty more answers

Posted from TSR Mobile

Reply 199

iiPablo

Original post by mgill17

Yeah, like it's never outright getting answers wrong, it's just forgetting little things or not using common sense then being like "Ahhh yeah I see that now" afterwards:/