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# Chemistry Unit 6B [6CH08][Edexcel][International Candidates][22.05.2012]

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1. Hey Guys!! Now how do i prepare for the upcoming UNITS???
Plus I think the chromatography can be improved by using more silica plates in a column chromatographic manner. This would cause more interaction with the stationary phase. (Just guessing)...
2. i just remembered that i accidentally wrote [Cr(NH4)6]3+ instead of [Cr(NH3)6]3+....totally ****ed up!!!
3. The % copper in was about 46.1 % it wouldnt make sense if it were 92.2%
4. how did you calculated the mass of cu in q3?
5. (Original post by sajidmatin)
It was a pretty good paper.

For HCl test, you can write bleaching of blue damp litmus paper, or white smoke with NH3 gas. It was two marks though, so it wrote both.
Yeah i wrote the same thing for this one. We'll only get one mark- if we're lucky. The question asked for a test for halides and then what you would observe for HCl. We were supposed to write the one with silver nitrate. I was so pissed when I realized. 1-2 marks gone !!!!
6. (Original post by laugh123)
The % copper in was about 46.1 % it wouldnt make sense if it were 92.2%
wrong! it completely makes sense if it was 92.2% ! lol ! u probably took the mass on 25cm3, we had to convert that to 250cm3 .....
7. (Original post by iesians)
wrong! it completely makes sense if it was 92.2% ! lol ! u probably took the mass on 25cm3, we had to convert that to 250cm3 .....
exactly
8. (Original post by gogo1994)
how did you calculated the mass of cu in q3?
i still rmb the no. of moles of Cu2+ in the sample being titrate is 3.05x10^-3
continue doing.... no of moles of Cu2+ in the coin: 3.05x10^-3 x 250/25 = 0.0305
mass of Cu2+ in the coin: 0.0305 x 63.5 = 1.93675 g
percentage : 1.93675/2.10 x 100% = 92.2%
9. ok everyone the moles of thiosulphate and Copper were same right ..?! why the heckkkkk was the question for 2 marks then ..?!??! did v have to show all the calculation like first halving it and then doubling it ! we would get the same f*****g answer ! i just wrtoe same as thiosulphates and wrote the value !!!! will i get 2 marks ??!?!?!?!!? i wanna bawl my eyes out nowwww !!!!!!!!! (((((((
10. (Original post by sasha_olemui)
i still rmb the no. of moles of Cu2+ in the sample being titrate is 3.05x10^-3
continue doing.... no of moles of Cu2+ in the coin: 3.05x10^-3 x 250/25 = 0.0305
mass of Cu2+ in the coin: 0.0305 x 63.5 = 1.93675 g
percentage : 1.93675/2.10 x 100% = 92.2%
Can u remember whether the number of moles in a coin was in a separate questions or not? Did it ask for the number of mole in the sample then the number of moles in the coin?

I know it sounds like a weird question to ask but just trying to remember whether i multiplied by 10 or not.
11. (Original post by bsblitter)
Can u remember whether the number of moles in a coin was in a separate questions or not? Did it ask for the number of mole in the sample then the number of moles in the coin?

I know it sounds like a weird question to ask but just trying to remember whether i multiplied by 10 or not.
it asked to find number of moles in coin in a second part ! and yes even i multiplied by 10 ! that is correct !
12. (Original post by bsblitter)
Can u remember whether the number of moles in a coin was in a separate questions or not? Did it ask for the number of mole in the sample then the number of moles in the coin?

I know it sounds like a weird question to ask but just trying to remember whether i multiplied by 10 or not.
nah it didn't ask for the number of moles in the coin, it asked directly for the mass of Cu in the coin in part c, then part d the percentage.
(or perhaps directly asking the percentage?? i can't quite rmb. but one thing i'm sure is that it didn't ask for the no. of moles in the coin :P )
13. greattttt i got that as well!

(Original post by iesians)
wrong! it completely makes sense if it was 92.2% ! lol ! u probably took the mass on 25cm3, we had to convert that to 250cm3 .....
14. (Original post by iesians)
it asked to find number of moles in coin in a second part ! and yes even i multiplied by 10 ! that is correct !
wasn't part b asking for the number of moles in the sample being titrate??
15. (Original post by sasha_olemui)
wasn't part b asking for the number of moles in the sample being titrate??
ummmmm im not sure ...i think it was part c which asked about the ORIGINAL SAMPLE ! so then part b shouldve been the one with the same answer as part A.....
16. guys if part b was same as part a , why was part b of 2 marks ..?!?!?!!!?!!?!? edexcel pisses me off !!
17. (Original post by iesians)
guys if part b was same as part a , why was part b of 2 marks ..?!?!?!!!?!!?!? edexcel pisses me off !!
yea part b same answer as part a.......i am confused too!!
seeing it worths 2 marks, i wrote one step.....divided it by two then multiply it by 2 ._. meaningless LOL
18. (Original post by sasha_olemui)
yea part b same answer as part a.......i am confused too!!
seeing it worths 2 marks, i wrote one step.....divided it by two then multiply it by 2 ._. meaningless LOL
lol ikr ! i wish i could have done tht ! i did all the calculation on calculator and when the answer was coming same i just wrote the same value ! without seeing its of 2 marks ! edexcel is so effin dumb !! will i get the marks ? whatdya think ?
19. (Original post by iesians)
lol ikr ! i wish i could have done tht ! i did all the calculation on calculator and when the answer was coming same i just wrote the same value ! without seeing its of 2 marks ! edexcel is so effin dumb !! will i get the marks ? whatdya think ?
Yeah that was weird I spent 5 extra mins just to make sure there wasn't some hidden trick that I missed out...

I think one mark for the answer and one mark for saying mol ratio is 1:1
20. i think i did the correct steps but i calculated the % incorrectly

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