I'm not even sure tbh, the questions are a blur now, I just remember doing (0.9/1.2)*100 at one point and getting 75%

EDIT: I think it was how much Mg can be produced from MgO, and it was 2 tonnes of MgO that could theoretically produce 1.2 tonnes of Mg. The next Q said that the actual yield was 0.9 and asked yo to calculate the %yield and suggest a reason for it.

(edited 9 years ago)

Reply 5

ak983

Original post by Rakes

Exam was pretty easy imho though writing the formulas were hard cos I didn't revise em��.

Though I still think B2 was easier.

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Why did gas needed to be bubbled through the solution of ions for the plant?

(edited 9 years ago)

Reply 6

S.Ahmad

Original post by AlphaNick

Because my calculation was 1.2/2.0 which was 60%. I swear the actual yield was 1.2 tonnes. I don't recall 0.9 tonnes or anything like that.

1.2 was the maximum yield and 0.9 was the amount they obtained.

Reply 7

Rubato

I got 2 tonnes and 75% they definitely gave the value 0.9

Reply 8

aoxa

It was ok, but I made so many stupid mistakes, and none of the topics I wanted to come up came up.

I also had a complete memory blank on the chromatography question. Ah well. I'll make up for it in C1.

Reply 9

mickel_w

Original post by AlphaNick

Because my calculation was 1.2/2.0 which was 60%. I swear the actual yield was 1.2 tonnes. I don't recall 0.9 tonnes or anything like that.

percentage yield = actual yield / maximum theoretical yield
1.2 / 2.0 = 60%

1.2 tonnes was the predicted amount of Magnesium produced (theoretical yield), which was in the first part of the question.

It then said, the actual amount produced was 0.9 tonnes. Calculate the percentage yield.

Hence 0.9/1.2 = 75%

Reply 10

Covington4

I also got 2 tonnes and 75%

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Reply 11

Yousf

i didnt write 2tonnes, for the relative atomic mass question, but i had my method spot on, i showed the balanced 2mg0, 24x2 and 16x2 showing 80, diving the 80 by 48, will i still get the 2/3marks...

Reply 12

ak983

Original post by AlphaNick

Oh, I assumed we had to use the results from the question like every single time it has been in the past.

AQA are just bastards, instead of actually testing your knowledge of the subject matter they try and dupe you out of marks by changing the layout of questions from previous papers- they did the same thing with geography. It's pretty disingenuous if you ask me, but anyway none of the papers have been hard so far in terms of content.

(edited 9 years ago)

Reply 13

tomb97

Original post by AlphaNick

I know here you went wrong. You used the tonnes that you'd calculated beforehand, but the question actually gave you a separate set of numbers from which you work out the percentage yield.

Reply 14

S.Ahmad

Original post by AlphaNick

Yeah that's the only thing I know I've got wrong so far, everything else I genuinely don't know but that's the only confirmed two marks I've lost. I might get one for the correct equation but who knows. Unit 3 was easy and the grade boundaries should be lower, hopefully I'll get high UMS in that one :tongue:

Hmm, I personally found C2 a lot easier, both were fairly easy. I've probably dropped 10 marks maximum on both papers, so hopefully in the boundary for an A*.