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2016 AQA GCSE Chemistry Unofficial mark scheme 2016

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Original post by possolik
I don't think the answer for distillation is right, because when you heat up the mixture even though all of the ethanol will have evaporated, some of the water will also evaporate before 100 degrees. Think about it logically, water on the ground evaporates even when the temperature isn't 100 degrees: temperature is the average kinetic energy of particles so some particles may have enough energy to evaporate even before 100 degrees.
So I think a more correct answer would be something like vapourise the mixture, then follow in a process similar to fractional distillation, where water vapour condenses at a lower level than ethanol, and they are separated this way.


I said for this one basically the process of distillation:

Filter in a beaker

Filter paper in the filter

Water in the beaker heated up

Ethanol poured into the filter (filter paper)

Ethanol has a lower boiling point than water and therefore evaporates into the condenser.

Condenser tube condenses the ethanol vapor back to a liquid.

Liquid is then dripped into a separate beaker.
Original post by possolik
I don't think the answer for distillation is right, because when you heat up the mixture even though all of the ethanol will have evaporated, some of the water will also evaporate before 100 degrees. Think about it logically, water on the ground evaporates even when the temperature isn't 100 degrees: temperature is the average kinetic energy of particles so some particles may have enough energy to evaporate even before 100 degrees.
So I think a more correct answer would be something like vapourise the mixture, then follow in a process similar to fractional distillation, where water vapour condenses at a lower level than ethanol, and they are separated this way.


Idk its unofficial and I think I'm going to keep it :smile:
Original post by LogicalFallacy
Definitely recycling, not reusing.


ahh yeah my bad. just couldn't remember. Can't even remember what I wrote mainly. some of the stuff in that first post (of mine) were what I wrote, what you think?
25 marks minimum.
What do you think the grade boundaries will be from an A* to a B?
I reckon: A* - 51
A - 42
B - 36
Original post by possolik
I don't think the answer for distillation is right, because when you heat up the mixture even though all of the ethanol will have evaporated, some of the water will also evaporate before 100 degrees. Think about it logically, water on the ground evaporates even when the temperature isn't 100 degrees: temperature is the average kinetic energy of particles so some particles may have enough energy to evaporate even before 100 degrees.
So I think a more correct answer would be something like vapourise the mixture, then follow in a process similar to fractional distillation, where water vapour condenses at a lower level than ethanol, and they are separated this way.


yeah I think you basically had to describe fractional distillation but with ethanol and water instead of crude oil
Original post by a_homida
What do you think the grade boundaries will be from an A* to a B?
I reckon: A* - 51
A - 42
B - 36


Now I feel like ****.
For the recycling question, would saying that it saves resources, is cheaper than reusing it because some parts might not work properly, and prevents pollution, be enough for 3 marks?
Original post by a_homida
What do you think the grade boundaries will be from an A* to a B?
I reckon: A* - 51
A - 42
B - 36


the grade boundaries will definitely high.
Original post by srmed
Was the two conditions for cracking: high temperature and hot catalyst


Posted from TSR Mobile


Would I get aluminium oxide catalyst?
I put that you should stir the water in the beaker to ensure even distribution of heat... is that ok or no?

Also the ethanol distillation one i just wrote about normal distillation not fractional? is that wrong?
Original post by chocolatewheel

Grade boundary predictions?


C1 past grade boundaries
2015: A* 50, A 41, B 31, C 22, D 13
2014: A* 47, A 38, B 29, C 21, D 13
2013: A* 47, A 37, B 27, C 17, D 8

I reckon this year was most similar to 2015 in terms of difficulty so use that
Original post by evebennettx
I put that you should stir the water in the beaker to ensure even distribution of heat... is that ok or no?

Also the ethanol distillation one i just wrote about normal distillation not fractional? is that wrong?


Normal distillation should be correct. It said nothing of fractional distilliation in that question and also, Crude oils are used in that scenario not the separation of ethanol from water.
no the balancing isn't 4Fe it is 2Fe then little 2
Original post by a_homida
What do you think the grade boundaries will be from an A* to a B?
I reckon: A* - 51
A - 42
B - 36

i reckon about 56 for A*
Original post by #1Mathlete
C1 past grade boundaries
2015: A* 50, A 41, B 31, C 22, D 13
2014: A* 47, A 38, B 29, C 21, D 13
2013: A* 47, A 37, B 27, C 17, D 8

I reckon this year was most similar to 2015 in terms of difficulty so use that


this years was easier than last year
Screen Shot 2016-05-19 at 11.40.43.pngyeah i reckon it was normal!
Original post by redsoules
Normal distillation should be correct. It said nothing of fractional distilliation in that question and also, Crude oils are used in that scenario not the separation of ethanol from water.
Original post by lillyholmes
no the balancing isn't 4Fe it is 2Fe then little 2


Erm... Are you sure about that? I think you are wrong. 4Fe is definitely correct. The little 2 would interpret covalant bonding and we know that metals do not have these bonds.
yeh whoops its 4
Original post by redsoules
Erm... Are you sure about that? I think you are wrong. 4Fe is definitely correct. The little 2 would interpret covalant bonding and we know that metals do not have these bonds.


yeh it is alright well done

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