CHEM 5 AQA Unofficial mark scheme.

it's ruby
and i thinnk the bond angle is 90, coz six ligands are bonded!

Didn't want to quote your entire mark
Scheme so...

For the entropy question, like, the graph one. I put 100JK-1mol-1 cos I timesed the 0.1 by 1000 but gave the new units as 100 joules rather than 0.1 kilo joules think I'll get the marks?


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Didn't want to quote your entire mark
Scheme so...

For the entropy question, like, the graph one. I put 100JK-1mol-1 cos I timesed the 0.1 by 1000 but gave the new units as 100 joules rather than 0.1 kilo joules think I'll get the marks?


This was posted from The Student Room's iPhone/iPad App

b) 0.1 KJmol^-1k^-1 ΔS (3)

Quick point on this mark: the calculated gradient is positive, but to produce a graph like the one shown the entropy must be negative, so I believe the symbol was -ΔS:

If you do a straight line equation y = mx + c you get ΔG = (-ΔS)T+ΔH

Aside from that, it all looks good. Thanks!

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Thank you , yeah that is a good point. cant see them penalising that though it would be very harsh but who knows after giving us a ratio above 100%

Do you think I would get the marks for writing p4o10 has two allotropes for q1b. Also, for the 12 mark questions when it asked to state the reagent, I only wrote ammonia or hydrochloric acid, didnt state that it should be in excess, would that be ok?

Its different though - if the gradient was equal to the positive delta S then it messed up the next question

For the graph question, I didnt work out the gradient but I put J/k/mol3 and delta S. Would I loose all 3 mark?

by definition entropy is JK-1MOL-1 so i converted mine to that. I dont know if it makes any difference. also im sure it wasnt exactly on a line at the top of the graph so not exactly 0.1 correct me if im wrong.

They will have a specified range of answers. the numerical answers would make no odds as long as the units are changed accordingly.

but can delta S be represented by different units? probably but i dont know.

Anyone got an idea on what the grade boundaries will be?

Thanks for the mark scheme btw!

I think I got around 70/100 give or take a few marks! I'm hoping this is around an A but hopefully unit 4 will boost my mark up . This was definitely a horrible paper compared to previous ones so I think an A will be 69/70/71. Lowest I've seen is 71. Thanks for the mark scheme man, it's really put me at ease. The question which bothers me the most is the recharging cell one. Was the reaction we had to give when it was recharging i.e. the opposite to the normal reaction of the cell or did we have to give the normal reaction of the cell....It's driving me crazy!