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Where's everyone up to for chemistry /physics /biology ocr? Wat have u covered so far
Original post by R.abokor
Where's everyone up to for chemistry /physics /biology ocr? Wat have u covered so far


Chemistry - Just finished Enthalpy Changes
Biology - Just finished Mitosis and Meiosis
Reply 62
Hi,

Do u think that it's better to stick to OCR papers or is it worth doing other exam board papers such as Edexcel and AQA ?
Reply 63
The AQA and Edexcel questions are good but I'm not sure if it's really worth doing....
OCR are starting to change the style of questions every year now and they are becoming a bit more difficult. Doing only the OCR papers will not achieve the A* grade at A2 as there is always new contextualised questions that are coming up and cathching people out like 2015 papers.
Original post by Danllo
Hi,

Do u think that it's better to stick to OCR papers or is it worth doing other exam board papers such as Edexcel and AQA ?


I did all the boards; worth doing if you're continuing it to Uni and want basically a guaranteed A*. If you're content with either A/A* & not studying at Uni don't bother. (Related degrees count).
Original post by Danllo
The AQA and Edexcel questions are good but I'm not sure if it's really worth doing....
OCR are starting to change the style of questions every year now and they are becoming a bit more difficult. Doing only the OCR papers will not achieve the A* grade at A2 as there is always new contextualised questions that are coming up and cathching people out like 2015 papers.


Depends, if you understand the principles of what you're doing you can apply them anywhere.
Reply 66
[QUOTE=ForgottenApple;61841121]Depends, if you understand the principles of what you're doing you can apply them anywhere.

I need to get 75%-85% in both F324 and F325 to get my A in chemistry. Do you think that I should do the other exam board papers ? My UMS is not high enough for an A* anyway.. And I doubt that I'll get an A* in chemistry.
Reply 67
I am a gap year student and my module grades for chemistry were

F321 : 66/90 - B - 73%
F322 : 125/150 - A - 84%
F323 : 48/60 - A - 80%
F324 : 27/90 - U - 30%
F325 : 75/150 - D - 50%
F326 : 51/60 - A - 85%

I ended up with a grade C in chemistry last year and I completely flopped the A2 papers. I achieved 392/600 UMS. I am retaking both A2 papers this year, however, shall I retake F321 ? Is it worth me revising for it again ? If don't retake it, I will have more time to revise for the A2 papers but I will need at least an A and B in either F324 and F325. Please let me know what u guys think, thanks.
Original post by Danllo
I need to get 75%-85% in both F324 and F325 to get my A in chemistry. Do you think that I should do the other exam board papers ? My UMS is not high enough for an A* anyway.. And I doubt that I'll get an A* in chemistry.


dude if u can get A you can get an A* ; only A2 UMS counts for the 90%

Do it if you can stomach it. Especially the last couple years, exam boards copy each other, but as a general rule before ~ Jan 2010 are not very challenging.
Original post by Danllo
I am a gap year student and my module grades for chemistry were

F321 : 66/90 - B - 73%
F322 : 125/150 - A - 84%
F323 : 48/60 - A - 80%
F324 : 27/90 - U - 30%
F325 : 75/150 - D - 50%
F326 : 51/60 - A - 85%

I ended up with a grade C in chemistry last year and I completely flopped the A2 papers. I achieved 392/600 UMS. I am retaking both A2 papers this year, however, shall I retake F321 ? Is it worth me revising for it again ? If don't retake it, I will have more time to revise for the A2 papers but I will need at least an A and B in either F324 and F325. Please let me know what u guys think, thanks.

If you're aiming for A* don't retake f321, for maximum chances of an A retake f321 and possibly f322 as that's easy mode f324
Reply 70
[QUOTE=ForgottenApple;61841537]If you're aiming for A* don't retake f321, for maximum chances of an A retake f321 and possibly f322 as that's easy mode f324

Thanks for the advice man. I only want an A in chemistry (obvs would like an A*) but I need to get an A in Edexcel Maths aswell in order to meet my firm choice.
Original post by ForgottenApple
Hey Rabokor basically what ya gotta do is shove what ya been told into the formula.

Kw= [OH-][H+]
Kw = 1x10^-14 at 25 degreesals

We've been told that [OH-] = 100[H+]
so we substitute this back in (least I would).
Kw = 100 x [H+] x [H+] = 100[H+]^2

Now you can rearrange and solve for H+ which gives you the pH :smile:

I got 8 when I did it, so check with the ms to make sure I'm talking some sense!

Hi, thank you for the notes! Why do you do [H+] x [H+] and not just 100 x [H+], why 2 H+ and not just 1?
Original post by R.abokor
Where's everyone up to for chemistry /physics /biology ocr? Wat have u covered so far


physics - we've done electricity and module 1, 2 and we're on 3 at moments and centre of mass. my teacher is so slow
chemistry - we've done module 1, 2 and 3. starting 4 next week
Reply 73
[QUOTE=Hunnybeebee;61900193]Anyone want to help me with my ums and decide what units to resit/leave?

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F321 : 66/90 - B - 73%
F322 : 125/150 - A - 84%
F323 : 48/60 - A - 80%
F324 : 27/90 - U - 30%
F325 : 75/150 - D - 50%
F326 : 51/60 - A - 85%

=392/600 - C

These are my UMS scores (I am a gap year student). I am resitting A2 obvs, but shall I resit F321? I'm not retaking F322 and I'm not retaking the course work. Do u think that's a the best option ? I'd be happy to advise u on what exams to resit if u want.
Original post by morgantopham
Hi, thank you for the notes! Why do you do [H+] x [H+] and not just 100 x [H+], why 2 H+ and not just 1?


It was a substitution, originally Kw = [OH-][H+]
when [OH-] = 100[H+] we still need to multiply it by the [H+]
Original post by Danllo
F321 : 66/90 - B - 73% 10-15% increase
F322 : 125/150 - A - 84% 5-10% increase
F323 : 48/60 - A - 80% Useless because schools cheat
F324 : 27/90 - U - 30% Minimum 20%+ increase should happen
F325 : 75/150 - D - 50% Minimum 10%+ increase should happen
F326 : 51/60 - A - 85% Useless because schools cheat

=392/600 - C

These are my UMS scores (I am a gap year student). I am resitting A2 obvs, but shall I resit F321? I'm not retaking F322 and I'm not retaking the course work. Do u think that's a the best option ? I'd be happy to advise u on what exams to resit if u want.


Eh, depends on grade. Presumably you DON'T want (expect) an A*, so I'll tailor it for that.

F324 NEEDS redoing, F322 may as well be redone, as you can gain some valuable UMS there, with no major extra revision.

F321 is the introductory module, so this will be easier than the rest, if you're feeling like revising the basics again, may also help with F325, though only marginally.

F325 probably should be redone, but is a rather dense module so might add a lot to workload.
Yes a B is definitely possible and A is also possible.


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Not having coursework in the reformed A-Levels has been a revelation. I hate coursework. It really allows me to focus on the theory now.

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Can anyone explain what stoichometry actually is and why the ratio is not the same as the number of moles - can't seem to get my head round it.
I feel so stupid asking this now currently doing A2 chemistry and still don't get it :|
Original post by tcameron
Can anyone explain what stoichometry actually is and why the ratio is not the same as the number of moles - can't seem to get my head round it.
I feel so stupid asking this now currently doing A2 chemistry and still don't get it :|


Stoichiometry is just a way of relating two species that react, in a ratio.

EXAMPLE:

1A + 2B -> 3C

Now usually this would be written as A + 2B -> 3C but I've written the 1 to exaggerate the point.

Now say you have 1 mole of A and 2 moles of B, in this case THE STOICHIOMETRY is equal to the moles.

But if you have say 0.5 moles of A, you cannot say you have 1 mole of A can you. The stoichiometry is then only useful in determining how much of something you produce or react. So if you were told that the reaction goes to completion, you can work out how many moles of B and C you have, (Useful in equilibria).

So the stoichiometry ratios are
1A:2B:3C

So if you have 0.5 moles of A, you will react 2 x 0.5 = 1 mole of B and 3 x 0.5 = 1.5 moles of C will be produced.

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