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

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On the last question where we had to put the mass of the compound used (like a 4 mark calculation question) i vaguely remember putting 1.7g or something, and i doubted myself when asking around today. what did everyone else get?

Reply 381

Spepper90

I also put 1.7g or something. My method involved multiplying the mols by 2/3 because that was the ratio i think. My other friend multiplied it by 3/2 which i think was wrong...

Can anyone confirm?

Reply 382

Jacobic

Original post by jam277

Yeah. I wrote PH, then concentration of H+ ions, then I wrote measured with PH Meter. I've seen this question a lot and they accept that.

thank god some other people are saying this, my friend said something about using a gas syringe and measure the volume of oxygen :O wtf

Reply 383

AllUnits

Original post by Jacobic

thank god some other people are saying this, my friend said something about using a gas syringe and measure the volume of oxygen :O wtf

What would work too if there was gaseous oxygen given off. I can't remember the exact equation though.

Reply 384

ManPowa

I have the exam infront of me.. got a spare copy.. teacher gave me today as we had a chem lessson.. just was going through it with class to produce an unoffical mark scheme..

But everyone did stress that it was a horrible paper, very synoptic heavy and very physics based.. which is bad for many who do biology.... Also we wasnt tested on the core course content.. so basically the exam was bullshi*.. defo a re-sit in the summer..

anyone want any questions.. got the exam here??

Reply 385

tkoki1993

Original post by ManPowa

Could you uploaded the unofficial markscheme or at least the paper?

Reply 386

ManPowa

Original post by AliceMedawar

Your teachers can view the paper 24 hours after the exam, the actual mark scheme won't be up for ages (nov. I think) on a secure website, so it can be used as a mock. Such a hard paper! x

Reply 387

Sneg

yeah please :biggrin:

a part of the last question.. Its on about finding the unkown mass of some compound, i think it was like 4 marks? or even if you could find a way to upload the paper for everyone to see that would be very beneficial, thanks.

Reply 388

Darthdevidem

Original post by ManPowa

Could you scan and upload the paper?

If we all work together to make a unofficial mark scheme at least we'll all know how deep in the water each of us stand.

Hopefully UMS will go down so maybe there will be no need for a retake for you.

Reply 389

ManPowa

Original post by Sneg

yeah please :biggrin:

2K2FeO4 + 3NO2- + 2H20 === Fe203 = 3NO3- = 4KOH

The concentration of N02- in a sample of impure water is 6.0 x 10-6 mol dm-3.
What is the minimum mass of solid potassium ferrate needed to oxidise all of the N02- ions in 1000dm3 of the pure water? :confused:

(4 marks)

Reply 390

doobucks

Original post by ManPowa

(4 marks)

the concentration of K2Fe04 would be 4.0*10^-6 mol dm-3 via ratio.
I then did number of moles of K2FeO4=Concentration times volume i.e.
4.0*10^-6*1000
that is the number of moles needed. so then i found the molar mass of K2FeO4 and times the molar mass by the number of moles to get the mass.

Reply 391

hidden_desire

Original post by jam277

I'm pretty sure I did the same thing....

Reply 392

doobucks

Original post by hidden_desire

I'm pretty sure I did the same thing....

Phew. I only got better at moles equations like in the holidays even though I did chemistry for a year. I'm sure that's right. At least I might have a hope of getting an A* so I don't have to resit to get 90%. How did you find the test?

Reply 393

hidden_desire

Original post by jam277

Lmao, I hope you do get that A*! I'll be over the moon to get an A :rolleyes:

Erm to be brutally honest, I didn't think it was really that hard - as in there weren't any questions that completely threw me. My main downfall is the problem I've been trying to battle for a while now, which is my terrible exam techniques, impulsivity and NOT READING THE QUESTION PROPERLY. And making avoidable mistakes. And not adding things in that I know I should have done :bawling:

Aaah well. Fingers crossed :smile:

Reply 394

doobucks

Original post by hidden_desire

Lmao, I hope you do get that A*! I'll be over the moon to get an A :rolleyes:

Aaah well. Fingers crossed :smile:

Yeah I know, the test was easy but i made so many stupid mistakes, I'm scared that I might have to resit since my teachers will probably not want me to resit and say i can do good in the next module but i'm not risking that.

Reply 395

sanaaa

ive like totally forgetten the exam questions ! LOL

Reply 396

doobucks

Original post by sanaaa

ive like totally forgetten the exam questions ! LOL

Lol. I need to get the paper somehow. So I can find out my potential marks. I'm angry I made so many stupid mistakes. I could have so easily completely Aced this paper, the thing is my teachers probably won't let me resit if I get 80% even though I want an A*

Reply 397

Cinamon

Original post by jam277

Won't let you resit? I can't believe they have that much control over those kind of choices.

Reply 398

doobucks

Original post by Cinamon

Won't let you resit? I can't believe they have that much control over those kind of choices.

I got a high B in my january exam, they didn't allow me to resit it in june because they said the next module was harder. I got an A in the next module and the coursework with the same amount of effort put into the first module but I got a B overall, then I asked to resit my B and they said I should do it in the summer. I was 1 UMS away from an A in AS, I'm so angry with them.