Chemistry unit 4 AQA

Do you do AQA physics? I thought the mod 4 paper was lovely :/

I do, well I guess I'm exaggerating how hard it was, I suppose it was ok, it's just that now I'm not so sure I'll live up to my A* prediction!

Reply 581

Erotas

Thanks for all the answers to my previous question.

How does nitric acid act a proton acceptor or base in the reaction with sulphuric acid. I don't understand where it accepts a hydrogen.
2H2SO4 + HNO3 >>>>> 2HSO4- + H30+ + NO2+

(edited 12 years ago)

Reply 582

Vinz93

Original post by Erotas

Thanks for all the answers to my previous question.

How does nitric acid act a proton acceptor or base in the reaction with sulphuric acid. I don't understand how it where it accepts a hydrogen.
2H2SO4 + HNO3 >>>>> 2HSO4- + H30+ + NO2+

It does it in single reactions...the one you have posted above is the overall combined reaction of 2 single reactions.

H2S04 + HN03 > H2NO3+ + HS04-

H2NO3+ > NO2+ + H20

combine em to get H2SO4 + HNO3 > NO2+ + HSO4- +H20

but the mark scheme always has it down as your one :s they seem to love the hydroxonium ion lol

Reply 583

Erotas

Original post by Vinz93

It does it in single reactions...the one you have posted above is the overall combined reaction of 2 single reactions.

H2S04 + HN03 > H2NO3+ + HS04-

H2NO3+ > NO2+ + H20

combine em to get H2SO4 + HNO3 > NO2+ + HSO4- +H20

but the mark scheme always has it down as your one :s they seem to love the hydroxonium ion lol

Oh right! Thank you :smile:

Do you think we could be asked to give the equation to show that it acts as an acid, in which case I'd also have to learn these?

Reply 584

al_habib

1

Original post by Erotas

Thanks for all the answers to my previous question.

How does nitric acid act a proton acceptor or base in the reaction with sulphuric acid. I don't understand where it accepts a hydrogen.
2H2SO4 + HNO3 >>>>> 2HSO4- + H30+ + NO2+

looking at the reaction h2SO4 has been oxidised to hSO4 where hydrogen has been lost, while h2SO4 donated the hydrogen is an acid(proton donor), hNO3 acid is described as proton acceptor.

Reply 585

zozoe

Sooo in the June 11 paper there was pretty much nothing about aldehydes and ketones or carboxylic acids and esters. Thinking they're probably gonna come up, and also maybe isomerism because there was nothing about that in the last paper either?

Reply 586

Vinz93

Original post by Erotas

Oh right! Thank you :smile:

Do you think we could be asked to give the equation to show that it acts as an acid, in which case I'd also have to learn these?

Doubt it but imagine it like this.

The H2SO4 acts as an acid and donates H+ ion, HN03 acts as a base and accepts H+ ion. sulfuric ACID

so

you get the H2NO3+ produced and you need to produce the nitronium ion from there, right?

so you start off in 2nd step with HNO3+ > NO2+ ... and you add H20 to make up the numbers

Reply 587

Erotas

Ahh got it! Thanks for the help everyone :smile:

gonna just do a few more questions, go over everything once before I go to bed, then go over everything again at school!
Would be ace if I got an A* but will be more than happy to get an A.
Good luck everyone!! Hopefully there won't be many of us in the resit thread :tongue:

Reply 588

Besakt

3

Original post by NuclearFusion

I did indeed :smile:

plus I'm doing Physics at Uni

And you find chemistry difficult?
Physics is much harder than chemistry.

Reply 589

al_habib

1

Original post by Besakt

And you find chemistry difficult?
Physics is much harder than chemistry.

that is true

Reply 590

paul272

what does mark scheme mean by penalise sticks,

Reply 591

rommy123

Good luck everyone, Hopefully the exam will be easy and we`ll all get the grades we need :biggrin:

Reply 592

handsome7654

Original post by Besakt

And you find chemistry difficult?
Physics is much harder than chemistry.

I disagree!
Physics is a hell of a lot easier than chem (Well at A-level). At uni physics is in a whole new league though! :tongue:

Reply 593

NightBear

12

The thought of sitting this exam frightens me.

Reply 594

wannabeme

8

Actually giving up on synthesis conditions, just gonna have to hope they dont come up to much :/

Reply 595

freddy

hi!, if they give you ph of sulphuric acid, we do inverse log - [ph]
and then times by two or divide???

Reply 596

freddy

Original post by NightBear

The thought of sitting this exam frightens me.

dont worry we will be fine, at least we can resit in summer!!!!! :smile:

(fingers crossed we wont have to though)

(edited 12 years ago)

Reply 597

AJCSShp

16

I think I am going to fail this exam tomorrow, I am dreadful at the buffer solution calculations, and organic synthesis. I have a feeling that this exam will be very nasty as well.

Reply 598

neekha

hey guys is the mechanism for aspirin production on the spec? Would very much appreciate if you could help me out! Totally panicking here :frown:

Reply 599

SoftMusk

10

just done two past papers, left 2 more to do tomrow then will go over them to refresh my mind, good luck everybody and get a good nights sleep...i hope its easy

Chemistry unit 4 AQA

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