AQA GCSE Chemistry Unit 2 24 May 2012

'can someone tell me the answer to 'why is the yield of ammonia increase when pressure is increased?'
Or whatever that question was?
I'm pretty sure i wrote because there are less reactant than product molecules

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Reply 321

R.P.Everything.

6

Original post by s.s.s

how many ums will 34/35 in this exam be???

If grade boundaries stay the same as last year, 84/87.

Original post by tssf_skye

'can someone tell me the answer to 'why is the yield of ammonia increase when pressure is increased?'
Or whatever that question was?
I'm pretty sure i wrote because there are less reactant than product molecules

It's the other way round - More reactant moles than product moles, so an increase in pressure sees an increase in the rate of reaction.

Reply 322

s.s.s

the asw is cos there r more moles of reactants then products...

Reply 323

siobhan-k

I was devastated at this exam, i did 3 mocks and got two A*'s and one A, was really hoping for that in todays exam but i think i completely messed up. :'(

Reply 324

siobhan-k

Original post by SophieLisa96

i felt exactly the same!

This is exactly how i felt too!

Reply 325

omega25

1

i failed on that question with the ions :') and what did everyone get for that question about how much ammonia can be made from 2g of nitrogen? i didnt get that...

Reply 326

Ashley is a baws

Original post by omega25

i failed on that question with the ions :') and what did everyone get for that question about how much ammonia can be made from 2g of nitrogen? i didnt get that...

i failed so hard 1st try at that question then i crossed everything out then tried again and got some like 2.48? i cant remember but some retarded number anyway...

Reply 327

Maat

unofficial mark scheme anyone?

Reply 328

Akb_1e3

Original post by tssf_skye

'can someone tell me the answer to 'why is the yield of ammonia increase when pressure is increased?'
Or whatever that question was?
I'm pretty sure i wrote because there are less reactant than product molecules

This was posted from The Student Room's iPhone/iPad App

I think you wrte it the wrong way round, there are more gaseous reactants than products

Reply 329

hello my name is

Original post by alicea12

That's what I put, as I assumed you do 3x20

yeeesssss i did the same :biggrin:

Reply 330

Maat

would, because the reaction is endothermic get the mark?

Reply 331

Maat

'why is the yield of ammonia increase when pressure is increased?'
would: because the reaction is endothermic get the mark??

Reply 332

tssf_skye

15

Original post by R.P.Everything.

If grade boundaries stay the same as last year, 84/87.

It's the other way round - More reactant moles than product moles, so an increase in pressure sees an increase in the rate of reaction.

Oh my god that is so annoying I wrote more and crossed it out to write less :|

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Reply 333

R.P.Everything.

6

Original post by Maat

'why is the yield of ammonia increase when pressure is increased?'
would: because the reaction is endothermic get the mark??

unfortunately no - the question was to do with the moles of reactants compared to the moles of products.

Reply 334

RdBlAdE

i though the reaction was exothermic because if it was endothermic, the best yield would be produced at high temperatures. (endothermic= takes in heat during reaction)

Reply 335

tssf_skye

15

Original post by hoanganhbeo96

Of course it is right. Well done :smile:

Someone just told me its the other way around :/

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Reply 336

R.P.Everything.

6

Original post by RdBlAdE

i though the reaction was exothermic because if it was endothermic, the best yield would be produced at high temperatures. (endothermic= takes in heat during reaction)

It is exothermic.

But for the pressure question (why does yield increase at higher pressures), that is more related with moles of reactant and moles of product.

Reply 337

maxtate

Original post by kman123456

For the question on 'Why is the yield of ammonia increased when pressure is increased?' I put ' there's less molecules on the right hand side then on the left, pressure Favors the side with the least amount of molecules''. is that right?