Competition - post a photo you've taken of nature >>

AQA Chemistry New AS Unofficial Mark Scheme

Scroll to see replies

Reply 60

hbaig27

Original post by A.aaa

No but they expect you to add them

So is it wrong if you didnt?

Reply 61

haes

Original post by hbaig27

Did the ionisation energy question say it needed state symbols?

all past paper questions about Ionisation energy say in the mark scheme that you must include state symbols

btw the equilibrium mpc question... i can't remember which was which but was the answer C or D?

Reply 62

britishtf2

Original post by haes

I can't remember which it was, but I put the endo one, that is the one you're one about.

Reply 63

vignesh1234567

Was the paper out of 80?

How many marks will I lose if I used the 3 titres but not the rough titre and calculated mR correctly? Will I get ecf?

Have the grade boundaries always been 80% (i.e. 64/80) for A?

Reply 64

britishtf2

Original post by vignesh1234567

1) Yes
2) I used all 3, but wasn't sure. Thinking back I think you (and I) will lose 1 mark. Should get ECF.
3) Usually adjusted slightly, but 80UMS is always an A. It will probably be ~80% for an A.

Reply 65

haes

Original post by vignesh1234567

yes, probably lose one mark, and apparently :/ but we're the first year for this spec, the first year for those damn multiple choice questions and honestly this was the hardest chemistry paper i've ever seen (minus the specimen paper) so hopefully they will lower it (75% would probably be the least it would be lowered to if it was)

Reply 66

hbaig27

This is significantly harder than old spec so the boundaries have to drop?

Reply 67

rosemondtan

guys it's unlikely that you'll lose all 3 marks for a question when you use one wrong value if the rest of your working is correct right?

Reply 68

britishtf2

Original post by rosemondtan

guys it's unlikely that you'll lose all 3 marks for a question when you use one wrong value if the rest of your working is correct right?

Very unlikely.

Reply 69

haes

Original post by vignesh1234567

Thanks; what did you guys put for the improvement to the burette procedure (and justify)?

add a greater volume in the conical flask (idek if there was a conical flask)
because this would mean the volume of the titre needed to neutralise the solution would be greater, and therefore the percentage uncertainty would decrease
(i didn't refer to the names of anything because i left this question last... i hope i still get the mark)

Reply 70

vignesh1234567

Original post by haes

Thanks britishtf2, haes, what did you guys put for the improvement and justification to burette procedure?

Reply 71

britishtf2

Original post by vignesh1234567

Thanks britishtf2, haes, what did you guys put for the improvement and justification to burette procedure?

Something along the lines of use more stuff cos you get a larger reading. I can't quite remember the question: sorry!

Reply 72

rosemondtan

Original post by britishtf2

Very unlikely.

lol omg it's so scary because if I add all the marks I've lost (assuming I get the entire question wrong) it's 10 marks but if i count method marks it's only 5 so idk omg lmaO)

Reply 73

vignesh1234567

Original post by britishtf2

Something along the lines of use more stuff cos you get a larger reading. I can't quite remember the question: sorry!

Thanks, np; did we have to assume that the bromine was protonated for the TOF graph?
Did you say that chlorine from the chlorate displaces the iodide?

Reply 74

britishtf2

Original post by rosemondtan

lol omg it's so scary because if I add all the marks I've lost (assuming I get the entire question wrong) it's 10 marks but if i count method marks it's only 5 so idk omg lmaO)

Is this question 3, where you used an extra value from the table? If so, you'll most likely lose 1 mark and have ECF for the rest of the question.

Reply 75

britishtf2

Original post by vignesh1234567

Thanks, np; did we have to assume that the bromine was protonated for the TOF graph?
Did you say that chlorine from the chlorate displaces the iodide?

For the graph, I think it should be 25%:50%:25% at 158:160:162. I could be wrong. I put 3 peaks at 33% though. I think it was 2 marks, so if this is the case, I think it is 1 mark for 3 peaks on correct values and 1 mark for correct percentages. I could be wrong about everything above though - just my thoughts!

For the chlorate, I put "I2 - black solid" because I had run out of time - I cannot remember the details of this question, and I don't think I could help you here if I did. Sorry about that!

(edited 7 years ago)

Reply 76

rosemondtan

Original post by britishtf2

Is this question 3, where you used an extra value from the table? If so, you'll most likely lose 1 mark and have ECF for the rest of the question.

and a few other questions :frown:

I think I used a wrong Mr value for one of the questions but my working was fine

Reply 77

britishtf2

Original post by rosemondtan

and a few other questions :frown:

I think I used a wrong Mr value for one of the questions but my working was fine

For each error like that you should only be penalised once with ECF. With errors where you say something like "covalent" where "ionic" is appropriate, you are often penalised with "CE = 0", or "Chemical Error = 0". For this, you lose all marks for that part of the question, and that part only.

Obviously there are exceptions.