Aqa a2 chem5 19th 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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Re: Aqa a2 chem5 19th june 2012Yep. Reduction using Zn/H+ (Zinc in acidic solution) and an inert atmosphere.
Cr3+ + e- ---> Cr2+
Overall reaction: Zn + 2Cr3+ ---> Zn2+ + 2Cr2+
Cr2+ is so unstable that it oxidises back to Cr3+ in air. -
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Re: Aqa a2 chem5 19th june 2012Me too
I'm doing cobalt now, and in the CPG book it says [Co(NH3)6]^3+ is dark brown, but the nelson thornes book says its yellow
and CGP says [Co(NH3)6]^2+ is straw coloured, and nelson thornes says its a brownish complex
do you know which is right? -
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Always include the electrodes, they may not always be made of platinum though.(Original post by myoaontw)
thank you! it made sense
does anyone know how you know if a conventional cell diagram is supposed to include platinum? is it if they're non metals?
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Re: Aqa a2 chem5 19th june 2012I apologise if that somehow affected you(Original post by . . .)
****ing hell. Chill out.
But, turns out that there is no need to spam the thread. People will answer and help if they can, spamming is just going to annoy people.
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[Co(NH3)6]^3+ dark brown on previous mark schemes(Original post by helpme12345)
Me too
I'm doing cobalt now, and in the CPG book it says [Co(NH3)6]^3+ is dark brown, but the nelson thornes book says its yellow
and CGP says [Co(NH3)6]^2+ is straw coloured, and nelson thornes says its a brownish complex
do you know which is right?
[Co(NH3)6]^2+ definitely straw coloured
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Re: Aqa a2 chem5 19th june 2012ahh right thanks, is there any way to know that they're gonna be made of platinum? my general chemistry knowledge is slightly lacking(Original post by Matthew692692)
Always include the electrodes, they may not always be made of platinum though.
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Re: Aqa a2 chem5 19th june 2012Sorry, my time machine needs fixing atm. It needs a new toaster.(Original post by I.LoveSyria.Aleppo)
what topics are most likely to come up in the exam?? -
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Re: Aqa a2 chem5 19th june 2012Ja. Straw coloured! Trust CGP more than the others. God knows the number of times I'd argued with my teachers over "Well, MY book says.... YOUR books say.."(Original post by helpme12345)
Me too
I'm doing cobalt now, and in the CPG book it says [Co(NH3)6]^3+ is dark brown, but the nelson thornes book says its yellow
and CGP says [Co(NH3)6]^2+ is straw coloured, and nelson thornes says its a brownish complex
do you know which is right?
... *sigh*
Relax. I've only done revision cards for the colours. Everything else is fine for me
So glad I revised during half term!!
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Re: Aqa a2 chem5 19th june 2012(Original post by wenger16)
yes oir you can use hcl.You can use zinc but you have to use it with HCl, i.e it has to be acidified. It's not an and/or situation I'm afraid
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Re: Aqa a2 chem5 19th june 2012I seem to do worse in June(Original post by wibletg)
I felt alright about Physics and the paper was alright as well
It's just AQA have given us a crappy paper every session since June.
I need 70 for an A.
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Re: Aqa a2 chem5 19th june 2012Papers are written around 3 years before being published to use... It's annoying.(Original post by wibletg)
I felt alright about Physics and the paper was alright as well
It's just AQA have given us a crappy paper every session since June. -
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Re: Aqa a2 chem5 19th june 2012If there's no other solids present in the reaction then you use platinum.(Original post by myoaontw)
ahh right thanks, is there any way to know that they're gonna be made of platinum? my general chemistry knowledge is slightly lacking -
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Re: Aqa a2 chem5 19th june 2012Stewie Griffin has got one going spare.(Original post by James24993)
Sorry, my time machine needs fixing atm. It needs a new toaster. -
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Re: Aqa a2 chem5 19th june 2012There's a reason for that, it doesn't react, due to the macromolecular structure(Original post by CollateralElement)
Anyone know the SiO2 reaction with water? It isn't in my books :/ It only reacts with conc NaOH because it's an acidic oxide..
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Re: Aqa a2 chem5 19th june 2012There isn't one. It's insoluble.(Original post by CollateralElement)
Anyone know the SiO2 reaction with water? It isn't in my books :/ -
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Just go for platinum unless it says otherwise, because thats what it usually is. Platinum is always used on the SHE.(Original post by myoaontw)
ahh right thanks, is there any way to know that they're gonna be made of platinum? my general chemistry knowledge is slightly lacking
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I'm so scared!
So glad I revised during half term!!
