Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012
Chemistry exam discussion - share revision tips in preparation for GCSE, A Level and other chemistry exams and discuss how they went afterwards.
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Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Thought i'd create a thread for this as the exam is in 4 days!
Hows revision going for everyone? This is a resit for me so i've only just started revision
, but the papers seem to be getting harder each year!
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Got the exam! I've revised a ridiculous amount. I did c1 c2 c3 in January and got a 100%, so hoping I can recreate that! Anyone else found the chemistry modules mind boggling long -_-. i'm most woried about a stupid precipitate questions- apparently this came in the new spec so ovbiously it will be in the exam.
Grade boundaries that low?! Really? I always view 90% as what I need to minimum achieve, if I get that I'm guaranteed an A*
Fingers Crossed! -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Could someone help me with a question? It is in the Jan 2010 paper ( http://pdf.ocr.org.uk/download/pp_10...e_a322_02.pdf? ) And it is question 4)c)ii). The answer is CuBr2 and I am unsure of how that is the answer. Thanks!
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Okay so Copper is Cu2+ and, by looking at the periodic table, you can find out that Bromine (to make CopperBromide) is Br- so in order to balance the elecetrons you will need 2 lots of the Br to balance the Cu. This is written as CuBr2 (little 2 but I can't seem to get that on here) Does that make a bit more sense..? Sorry, it's quite hard to explain.. hope this sorta helps though(Original post by Ingamo)
Could someone help me with a question? It is in the Jan 2010 paper ( http://pdf.ocr.org.uk/download/pp_10...e_a322_02.pdf? ) And it is question 4)c)ii). The answer is CuBr2 and I am unsure of how that is the answer. Thanks!
Last edited by sinead123; 25-06-2012 at 09:09. -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012How do you know that Bromine is br- from looking at the periodic table? Is it because it has one electron in its outer shell?(Original post by sinead123)
Okay so Copper is Cu2+ and, by looking at the periodic table, you can find out that Bromine (to make CopperBromide) is Br- so in order to balance the elecetrons you will need 2 lots of the Br to balance the Cu. This is written as CuBr2 (little 2 but I can't seem to get that on here) Does that make a bit more sense..? Sorry, it's quite hard to explain.. hope this sorta helps though
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Okay so the Halogens are Group 7, this means they have 7 electrons in their outer shell. They all need to gain 1 electron to complete their outer shell, this means (from their normal state as an element) they need to gain 1 negative electron to complete their outer most shell - this would give them a -ve charge. All Halogens are 1-(Original post by Ingamo)
How do you know that Bromine is br- from looking at the periodic table? Is it because it has one electron in its outer shell?
any better?
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Ah yes I was supposed to say they need to gain one electron haha! Thanks so much that helps a lot!(Original post by sinead123)
Okay so the Halogens are Group 7, this means they have 7 electrons in their outer shell. They all need to gain 1 electron to complete their outer shell, this means (from their normal state as an element) they need to gain 1 negative electron to complete their outer most shell - this would give them a -ve charge. All Halogens are 1- any better?
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Oh okay!(Original post by Ingamo)
Ah yes I was supposed to say they need to gain one electron haha! Thanks so much that helps a lot!
I'm glad it helped.. i'm not the best at explaining things... Best of luck today! I'm sure you'll do fab!
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Yeah, wasnt too hard really, the carbon cycle thing was a tad random :P
& the only answer i didnt know was the bit where you had to fill in the titration question table thingy.. anyone get this? -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Yeah that and a couple of others I found hard but otherwise it wasn't too bad!(Original post by kited4)
Yeah, wasnt too hard really, the carbon cycle thing was a tad random :P
& the only answer i didnt know was the bit where you had to fill in the titration question table thingy.. anyone get this? As last year it was only 27/42 for an A* I predict it'll be about 33/34 as they aren't allowed to increase the boundaries too much in a year apparently.
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Hmm i really want an A* because this was a resit and last time i got 43/50 UMS which was an A... and i want all that revision to be worth it!
Anyway that was my last exam so now i can finally relax!!!! -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Yeah I thought the carbon cycle one was odd too! For the titration one I just copied the trend of the others and wrote 40.00 for the top one but I had to leave the second one cos I hadn't a clue!(Original post by kited4)
Yeah, wasnt too hard really, the carbon cycle thing was a tad random :P
& the only answer i didnt know was the bit where you had to fill in the titration question table thingy.. anyone get this? -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Yeah same here, I noticed the trend and thought i'd put that in if I couldn't calculate it correctly. Every time I tried to calculate it I got huge answers which I just knew weren't right, so hopefully got 1 mark out of it(Original post by sinead123)
Yeah I thought the carbon cycle one was odd too! For the titration one I just copied the trend of the others and wrote 40.00 for the top one but I had to leave the second one cos I hadn't a clue!
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012For the titration one I got 40 and 60.1 or something... :L
The carbon neutral thing completely threw me off. I had no clue what it meant xD Apparently it means that the fuel doesn't take away or contribute any carbon into the atmosphere... For the answer I guessed and said that it "supports the carbon cycle and therefore is carbon neutral" haha... hoping for one out of three marks D:
Also, for the sodium and chloride symbol equation, I put down state symbols and put (liquid) for Sodium Chloride instead of (solid). In the 2009 past paper, the mark scheme for a similar question did not require the state symbols, only the correct numbers and letters, so I'm hoping that this time they won't mark me down for saying salt is a liquid -_- -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012Did the symbol equation even ask for state symbols? I thought you just had to write down NaCl2?(Original post by Missyeln213)
For the titration one I got 40 and 60.1 or something... :L
The carbon neutral thing completely threw me off. I had no clue what it meant xD Apparently it means that the fuel doesn't take away or contribute any carbon into the atmosphere... For the answer I guessed and said that it "supports the carbon cycle and therefore is carbon neutral" haha... hoping for one out of three marks D:
Also, for the sodium and chloride symbol equation, I put down state symbols and put (liquid) for Sodium Chloride instead of (solid). In the 2009 past paper, the mark scheme for a similar question did not require the state symbols, only the correct numbers and letters, so I'm hoping that this time they won't mark me down for saying salt is a liquid -_- -
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Re: Chemistry C4 C5 C5 - 21st Century Science - 25th June 2012it was 2NaCl not NaCl2 the full equation was "2 Na +Cl2 ---> 2NaCl"(Original post by sinead123)
Did the symbol equation even ask for state symbols? I thought you just had to write down NaCl2?
, but the papers seem to be getting harder each year!
