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AQA GCSE CHEMISTRY UNIT 2 HIGHER CHY2H January 2012 unofficial mark scheme

1a) i) They didn’t have the right equipment as it hadn’t been invented then. (1)
ii) Reaction is endothermic (1)
iii) Other scientists could not repeat his results (1)
iii) Aluminium chloride + potassium goes to Potassium chloride and aluminium (1)
b) He found the properties of aluminium and compared them to the properties of the previously discovered metals. He realised properties were different so must have been a new metal. (2)
2a) i) Relative formula mass MgO = 24 + 16 = 40 (2)
ii) Percentage mass of Mg = 60% (2)
iii) Mass of Mg from 25g MgO = 15g (1)
b) i) Some MgO lost when students lifted the lid (1). Not all of the Mg ribbon reacted when the students thought it had (1). Other answers as well (out of 2)
ii) It was more reliable as they could compare the data to check for a pattern and discard any anomalous results (2).
3a) Mg (2, 8, 2) and Cl (2, 8, 8) drawn. (2)
b) Filter (1)
ii) Hydrochloric Acid (1)
c) Ions are mobile (1)
ii) Chlorine ions lose electrons (1)
iii) Mg2+ + 2e- goes to Mg (1) (OR Mg2+ goes to mg - 2e-)
4. Fe2O3¬ (4)
5a) Giant structures containing layers of metal atoms. Free, delocalised electrons. (3)
i) Free electrons carry the heat (1)
b) i) Much smaller (1)
ii) Can fit into smaller gaps than normal-sized atoms (1) (Larger surface area?? make your own minds up, refer to conversation on p9 and 10 to see the debate!)
6a) Covalent (1)
b) More reactant molecules than product molecules (1)
ii) Reaction is exothermic (1)
c) More particles in the same volume of gas which means there is more chance of collisions, increasing the rate of reaction. (2)
d) Ethanol held together by weak intermolecular forces which require little energy to break (2)
7a) i) Graphene is strong as it has a giant lattice structure. Each carbon atoms is joined to 3 others by strong covalent bonds which require a lot of energy (force) to break. (3)
ii) Each carbon only joined to 3 other carbon atoms so free electrons carry the electric current through the graphene. (2)
iii) Screen would no longer be transparent/ layers would slide off meaning you get graphite all over your hands!!! (1)

Please post any improvements.
(edited 12 years ago)

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Reply 1
for gods sake.. i misssed out 3a...

wow...

only lost 5 marks altogether though (According to this mark scheme!)

:biggrin:
Reply 2
for question 5bii i put they have a larger surface area would i get the mark??
Reply 3
and for 7aiii i put that the layers are held by weak intermolecular forces so could be rubbed off
Reply 4
Original post by aimes12
for question 5bii i put they have a larger surface area would i get the mark??

I put the same, bit worried now!
and stupid me put that electricity would be carried not heat for question 5a!
(edited 12 years ago)
Reply 5
Original post by aimes12
and for 7aiii i put that the layers are held by weak intermolecular forces so could be rubbed off


I think you'd get both marks for weak (1) intermolecular forces (1). I don't know what you mean by "could be rubbed off" as wasn't it about evaporation. Anyway i think you would have got 2/2 on that question :smile:
Reply 6
Original post by zoologist7
I put the same, bit worried now!


Not sure!!
Reply 7
Original post by PoorLoser
for gods sake.. i misssed out 3a...

wow...

only lost 5 marks altogether though (According to this mark scheme!)

:biggrin:


you arent the only one who missed out 3a, loads of people did, i just thought it was part of a diagram and completely diregarded it, but atleast its only 2 marks :smile:
Reply 8
anyone got a mark scheme for C1? :smile:
Reply 9
Original post by metaltron
1a) i) They didn’t have the right equipment as it hadn’t been invented then. (1)
ii) Reaction is endothermic (1)
iii) Other scientists could not repeat his results (1)
iii) Aluminium chloride + potassium goes to Potassium chloride and aluminium (1)
b) He found the properties of aluminium and compared them to the properties of the previously discovered metals. He realised properties were different so must have been a new metal. (2)
2a) i) Relative formula mass MgO = 24 + 16 = 40 (2)
ii) Percentage mass of Mg = 60% (2)
iii) Mass of Mg from 25g MgO = 15g (1)
b) i) Some MgO lost when students lifted the lid (1). Not all of the Mg ribbon reacted when the students thought it had (1). Other answers as well (out of 2)
ii) It was more reliable as they could compare the data to check for a pattern and discard any anomalous results (2).
3a) Mg (2, 8, 2) and Cl (2, 8, 8) drawn. (2)
b) Filter (1)
ii) Hydrochloric Acid (1)
c) Ions are mobile (1)
ii) Chlorine ions lose electrons (1)
iii) Mg2+ + 2e- goes to Mg (1)
4. Fe2O3¬ (4)
5a) Giant structures containing layers of metal atoms. Free, delocalised electrons. (3)
i) Free electrons carry the heat (1)
b) i) Much smaller (1)
ii) Can fit into smaller gaps than normal-sized atoms (1)
6a) Covalent (1)
b) More reactant molecules than product molecules (1)
ii) Reaction is exothermic (1)
c) More particles in the same volume of gas which means there is more chance of collisions, increasing the rate of reaction. (2)
d) Ethanol held together by weak intermolecular forces which require little energy to break (2)
7a) i) Graphene is strong as it has a giant lattice structure. Each carbon atoms is joined to 3 others by strong covalent bonds which require a lot of energy (force) to break. (3)
ii) Each carbon only joined to 3 other carbon atoms so free electrons carry the electric current through the graphene. (2)
iii) Screen would no longer be transparent (1)

Please post any improvements.

Thanks ever so much for doing this though!
Probably got 1a, 5a)i and 5b)ii wrong so hopefully got 42 or 43 out of 45
(edited 12 years ago)
Reply 10
Original post by aimes12
and for 7aiii i put that the layers are held by weak intermolecular forces so could be rubbed off


you wouldnt get any, because it asked why it wouldnt be good with more layers, the question was trying to get you to realise that as the layers build up the transparency would be lost
Original post by aimes12
for question 5bii i put they have a larger surface area would i get the mark??


yeah i put that also.
Reply 12
For the last question I said the same thing but in a longer form. :tongue:
Reply 13
Original post by outsider95
you wouldnt get any, because it asked why it wouldnt be good with more layers, the question was trying to get you to realise that as the layers build up the transparency would be lost

Oh, yes, i was thinking of the wrong question ,sorry. Thank you for clearing it up! No you wouldn't get any ! Sorry.
Reply 14
Original post by zoologist7
Thanks ever so much for doing this though!


You're welcome!
Can you please give pos rating as my overall rating is terrible and seems to be going down every day !!!:s-smilie:
****ing hell! i did so ****
Reply 16
Original post by metaltron

ii) Hydrochloric Acid (1)


Oh God! I said 'hydrogen chloride'. What the actual..?! I was panicking because I was stumped on the first question! I can't believe it!!
Reply 17
Yep, should do. It is q1 after all!
Original post by zoologist7
I put the same, bit worried now!
and stupid me put that electricity would be carried not heat for question 5a!


I did exactly the same! I came out and everyone was like, "What did you put for the conducting heat question?" and I was like "What heat question? I thought it was about conducting electricity?". Dammit, saw the word 'conduct' and launched into a paragraph about conducting electricity without bothering to check.
Oh well, only one mark.
Hopefully the markscheme will give the mark for saying 'free electrons' :smile:
Reply 19
2a) i) Relative formula mass MgO = 24 + 16 = 40 (2)
ii) Percentage mass of Mg = 60% (2)
iii) Mass of Mg from 25g MgO = 15g (1)


OH THANK GOD!!!

I changed that first question at the last minute. Kept thinking it was 1.5 for some reason.

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