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OCR GCSE 21st Century Chemistry C1 C2 C3

Discussion about revision for the exam/how the exam went (when it has been sat).

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Reply 1
For me the B123 exam and C123 exam are exactly one month apart, so lots of revision time. We have done a lot in class. The B123 practice papers had only like 70%+ for an A* so if they are the same for the other exams then I should be able to get an A* easily, as on all the practice papers I've been getting A*s and dropping only like 3/4 marks. However the way UMS works means that this means nothing as far as I can see it.
The topics I am least certain on include:
Minerals in the Earth etc.
Atmospheric evolution
Polymers

The rest is just exam technique really. I don't think I need to do that much revision but I'm trying to do 1/2 an hour each day at least.

Practice questions for anyone who cares
1) Explain the different methods of obtaining salt and the uses that they are most suited to. (6)
2) Complete the following chemical equation:
Methane + Oxygen = __________ + _________
CH4 + 2O2 = __________ + _________
(3)
3) Match up the cause of an atmospheric change and the gas(es) it changed. Each cause and/or gas may have more than one line.
Volcanoes Nitrogen
Green plants Oxygen
Carbon Dioxide
(3)
4) State two ways that polymers can be changed and the properties that this affects.
Change 1 ________
Properties affected _____________________________________________________-
Change 2_________
Properties affected _____________________________________________________
(4)

5) When brine is electroysed, three products are formed. List them.
1___________
2___________
3___________
(3)

My answers (may be wrong)
1) Solution mining can be used to obtain salt. This entails pumping water into a salt deposit and then using the resultant brine as and when needed. It is suited to the chemical industry as the salt is relatively pure but has health risks attached to it. Salt mining can also be used to obtain salt. This entails using machinery to dig salt out of underground deposits. This is suited to use as rock salt or grit as the salt contains many impurities so cannot be used in the chemical or food industries. Finally, evaporating seawater can be used to obtain salt. This is suited to the food industry as the salt obtained is very pure.
2) = Water + Carbon dioxide
= 2H2O + CO2
3) Volcanoes -> Nitrogen, Carbon Dioxide
Plants -> Carbon Dioxide, Oxygen
4) Plasticization
It reduces forces between polymers, lowering their boiling point and making them more flexible.
Cross-linking
It chemicularly bonds polymer chains, increasing their boiling point, increasing forces between them and making them stronger.
5)Sodium Hydroxide
Hydrogen
Chlorine
Reply 2
Original post by Krollo
For me the B123 exam and C123 exam are exactly one month apart, so lots of revision time. We have done a lot in class. The B123 practice papers had only like 70%+ for an A* so if they are the same for the other exams then I should be able to get an A* easily, as on all the practice papers I've been getting A*s and dropping only like 3/4 marks. However the way UMS works means that this means nothing as far as I can see it.
The topics I am least certain on include:
Minerals in the Earth etc.
Atmospheric evolution
Polymers

The rest is just exam technique really. I don't think I need to do that much revision but I'm trying to do 1/2 an hour each day at least.

Practice questions for anyone who cares
1) Explain the different methods of obtaining salt and the uses that they are most suited to. (6)
2) Complete the following chemical equation:
Methane + Oxygen = __________ + _________
CH4 + 2O2 = __________ + _________
(3)
3) Match up the cause of an atmospheric change and the gas(es) it changed. Each cause and/or gas may have more than one line.
Volcanoes Nitrogen
Green plants Oxygen
Carbon Dioxide
(3)
4) State two ways that polymers can be changed and the properties that this affects.
Change 1 ________
Properties affected _____________________________________________________-
Change 2_________
Properties affected _____________________________________________________
(4)

5) When brine is electroysed, three products are formed. List them.
1___________
2___________
3___________
(3)

My answers (may be wrong)
1) Solution mining can be used to obtain salt. This entails pumping water into a salt deposit and then using the resultant brine as and when needed. It is suited to the chemical industry as the salt is relatively pure but has health risks attached to it. Salt mining can also be used to obtain salt. This entails using machinery to dig salt out of underground deposits. This is suited to use as rock salt or grit as the salt contains many impurities so cannot be used in the chemical or food industries. Finally, evaporating seawater can be used to obtain salt. This is suited to the food industry as the salt obtained is very pure.
2) = Water + Carbon dioxide
= 2H2O + CO2
3) Volcanoes -> Nitrogen, Carbon Dioxide
Plants -> Carbon Dioxide, Oxygen
4) Plasticization
It reduces forces between polymers, lowering their boiling point and making them more flexible.
Cross-linking
It chemicularly bonds polymer chains, increasing their boiling point, increasing forces between them and making them stronger.
5)Sodium Hydroxide
Hydrogen
Chlorine


Thanks helped a lot :biggrin:
Reply 3
How did everyone find the exam?
Original post by alj123
How did everyone find the exam?


HARD!!!:frown::mad::s-smilie::confused::angry:
I didn't actually find it too difficult! Some of the questions about graphs and data were a bit weird and the polymer graph about strength and stretchiness was quite confusing. Oh, and we hadn't learnt about electrolysis cells, but I thought all the 6 mark questions were really easy! :biggrin:
Reply 6
IMHO I thought it was quite easy, but all my friends said that it was very hard. It looked hard on the surface but when I got down to it, I found it quite easy.
Reply 7
I found this exam much easier than the biology! But i think that's because i'm beginning to learn the examiners technique. The last question was a bit of a guess though! :colondollar:
Reply 8
I think it was quite easy. Of course, there were a couple of questions that I struggled with but Chemistry is by far my weakest Science. I hope I've done enough to get the A that I want.
Reply 9
Hey guys, just need confirmation on a few questions:
> What was up with that table 2 calculation thing? :s-smilie: I got 14 in the end but I know it's wrong, I couldn't figure it out!
> Also, did you guys tick the boxes for energy input for making the material and the other energy input one?
> The last thing I wasn't sure about was that number of molecules one.. I put 4 molecules in total (the conservation of atoms) but there wasn't 4 molecules, there were more? :s-smilie:
Original post by kirstyjones <3
I didn't actually find it too difficult! Some of the questions about graphs and data were a bit weird and the polymer graph about strength and stretchiness was quite confusing. Oh, and we hadn't learnt about electrolysis cells, but I thought all the 6 mark questions were really easy! :biggrin:


yer i didnt like that question either i hope ive done alright tho cus i thought it ws quite hard
:s-smilie:
Reply 11
Am i the only person who found it hard? What do you think the grade boundaries will be? Hopefully they will be low..
Reply 12
Original post by Aidn
Hey guys, just need confirmation on a few questions:
> What was up with that table 2 calculation thing? :s-smilie: I got 14 in the end but I know it's wrong, I couldn't figure it out!
> Also, did you guys tick the boxes for energy input for making the material and the other energy input one?
> The last thing I wasn't sure about was that number of molecules one.. I put 4 molecules in total (the conservation of atoms) but there wasn't 4 molecules, there were more? :s-smilie:


Say whaaaat? I don't remember that :s
Reply 13
Original post by rudegyal
Am i the only person who found it hard? What do you think the grade boundaries will be? Hopefully they will be low..


I found it quite hard. I don't know what to expect really.
Reply 14
Original post by alj123
I found it quite hard. I don't know what to expect really.


Yeah same! The grade boundries for core students in january was 64% for an A*!!! hopefully it'll be like that for us!
Reply 15
I Found this exam quite good, there was some tricky questions though, if an A* is 64% (hopefully) well all do well, also does anyone have the answers for this exam?
Reply 16
Original post by rudegyal
Yeah same! The grade boundries for core students in january was 64% for an A*!!! hopefully it'll be like that for us!


Yes, hopefully.
If anyone has answers, please feel free to post them.
Reply 17
this exam was a ****ing joke and are you sure A* was 64%
Reply 18
I found this exam alright, how did everyone do on the six mark questions? Did anyone notice that there was one 6 mark question for c1 and 2 6 mark questions for c2 but no 6 mark question for c3.. that's weird..normally you would have expect to see one 6 mark question per topic - hopefully everyone does well !! (:
Reply 19
Original post by alj123
Say whaaaat? I don't remember that :s


Yeah, just realised that you're all doing the new spec..
I was doing a retake of the old one ¬_¬

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