OCR Salters F334 Chemistry of Materials (26/01/2011)

My school uploaded all of the chemistry past papers from about 2003 onwards including the most recent one. So if you want any just let me know.

Here's the mark scheme for June 2010 although I think it's on the ocr website as well.

What marks are you all getting in them, on average?

Here's the Jan 2010 mark scheme, hope it helps.

My school uploaded all of the chemistry past papers from about 2003 onwards including the most recent one. So if you want any just let me know.

Here's the mark scheme for June 2010 although I think it's on the ocr website as well.

What marks are you all getting in them, on average?

Do you have June 2010 for F334 by any chance?

My school uploaded all of the chemistry past papers from about 2003 onwards including the most recent one. So if you want any just let me know.

Here's the mark scheme for June 2010 although I think it's on the ocr website as well.

What marks are you all getting in them, on average?

How do you work out units for rate equations?

It's quite hard to explain when typing.
but.. basically you have your rate equation like.. rate=k[A]^2 for example.
Then to find the units of k, you sub in the units for each part.
so... moldm-3s-1 = k*(moldm-3)^2
=> moldm-3s-1 = k*mol2dm-6
k=(moldm-3s-1/mol2dm-6) so, k=mol-1dm-3s-1.
with all the -1, -6 etc being superscript. It's basic indices laws.

Hope that makes sense, if not.. sorry.

No, that sort of makes sense in all honesty, I'll just have to practice a bit.

The bit I do not get is that when you have (mol dm-3)^2 wouldn't you have to do:

Mol x Mol so Mol^2
Dm-3xDm-3 so Dm-3

But then after this also:

Mol x dm-3 twice and add it in? Or am I thinking totally wrong here?

It makes more sense if it's written on paper tbh, so your teacher will probably show it better.

But (moldm-3)^2.
In indices you can simply multiply the powers inside by the power outside. so it = mol^(1*2)dm(-3*2).
Or the other way to look at it being. Mol x Mol = Mol^2 (as you said, because when multiplying you add powers)
And then, dm-3 x dm-3 = mol^(-3+-3) = mol^(-6)

So you have; rate = k x (moldm-3)^2
from, rate = k[A]^2
So you just sub in your expanded brackets that you've calculated, and then rearrange to get k= ......
Then, simplify the indices again.

Sorry, yer I meant -6 in my thing. But I do get it know, so thank you very much

Ohhh, You don't happen to have the mark scheme to Jan 2009 do yaa? My school gave us the F331 mark scheme instead. Don't worry if you don't!

As for marks, I'm getting either strong A's or weak A's percentage-wise. But then I only have grade thresholds for some of the exams, and so sometimes actually I've done better than the percentage suggests. On Wednesday I think it could go either way, either scrape an A, miss an A or completely beast the test and full marks it. - Though not likely ahah, I can dream..

I get you. I'm getting low A's or medium A's. I think I'll beast the test for some reason I feel better for this than in F332 so I'll get a strong A at least. Usually 90% would give you 90/90 UMS because of grade boundaries.

Ha, I'm hoping the pressure will make me remember everything. But yeah, the grade boundaries change UMS so much. Like in F331, I got 90/90 UMS even though know I only really got about 90%. I'm feeling pretty confident though, its just if they ask for some theory that I completely forget in the moment. That, or I'll forget a particular word that they want.. Otherwise I'll take educated guesses, and hope for the best.
I sooo want a question on recrystallisation/tlc/electrochemical cell setups. Easy marks.

Yeah same here, though I flopped F331 and got a B which messed up my grade for AS, missed an A by 1 UMS because of that exam and I wasn't allowed to resit, I was angry at my teachers for that but now I just have to make sure I do better in this, looking for at least 90%.

Ah, that happened to me in French! 2UMS from an A. I suppose if you manage to get a strong A in this, and then a strong A in coursework, it takes alot of pressure off the summer exams. I'm hoping to rank up as many UMS marks possible to allow a flop in the last exam, and still hopefully end out with an A. A* has completely left my mind these days!