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# OCR B (Salters) F332 Tuesday 4th June 2013 Exam Discussion (Now Closed) watch

1. (Original post by EstebanK0)
Ah man. I put 2,6-dimethyloct-5ene
Initially put down 3,7-dimethyloct-3-ene but scribbled it out.
I put the same as you did, don't worry I'm pretty sure the mark scheme will accept both - in past papers they always do
2. (Original post by Davelittle)
No just NaCl, the 2:1 ratio of NaCl meant you had to half the moles of NaCl (not multiply the Mr by 2)
I did 2 NaCl them divided the no. of moles by 2 :/

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3. (Original post by Davelittle)
It didn't ask for sig fig so I put 41025dm^3

Seems right to me though!
might lose 1 mark for accuracy?
4. (Original post by Davelittle)
Q 1. Was 3,7-dimethyloct-3-ene
I put 2,6 because don't we have to use the lowest numbers. I think I forgot to write di :/

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5. (Original post by Davelittle)
No just NaCl, the 2:1 ratio of NaCl to Cl2 meant you had to half the moles of NaCl (not multiply the Mr by 2).
That should come out as the same thing, as long as they didn't use half of the moles AND multiply the Mr by 2, I think.
6. (Original post by super121)
Didn't we have to work out the Mr of 2NaCl, apart from that I did the same steps

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no, moles = mass/Mr... the 2NaCl is significant because you divide the number of moles of NaCl by 2 to get I mole of Chlorine
7. (Original post by juniorx)
might lose 1 mark for accuracy?
Why would it? They didn't specify the number of significant figures, did they? Unless the actual answer is wrong. xD
8. Is the possible structure of the last section of Q1? Hope I remembered it well

9. (Original post by abzy1234)
Is the possible structure of the last section of Q1? Hope I remembered it well

exactly i swear this can also be 2 ethyl 6 methyl hept 2 ene with the ethyl as that long bit at the top right?
10. (Original post by super121)
x
I don't think you multiply it by 2, as it'll cancel down anyway, as it's a 2:1 ratio I think.

If you got the final answer, regardless, you'll pick up the mark
11. (Original post by juniorx)
exactly i swear this can also be 2 ethyl 6 methyl hept 2 ene with the ethyl as that long bit at the top right?
I'm not too sure, as the top right part can be part of the main carbon chain. It's a complicated structure, so I'm sure they will have a variety of ways of answering it
12. (Original post by ActaNonVerba)
no, moles = mass/Mr... the 2NaCl is significant because you divide the number of moles of NaCl by 2 to get I mole of Chlorine
I know that. I did the Mr of 2 NaCl (117 I think). (200000/117)/2 to get moles of Cl2 them multiplied that by 24.

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13. Anyone else hate that last 6 mark question on the advance notice? Thought the paper was going alright up until I got to that question, I didn't have a clue!

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14. (Original post by ambbs)
Anyone else hate that last 6 mark question on the advance notice? Thought the paper was going alright up until I got to that question, I didn't have a clue!

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I quite liked it, actually. xD My main problem was trying not to copy the article...
15. (Original post by juniorx)
if this is wrong can someone tell me why it is wrong?
Well the longest carbon chain was 8, the double bond was between the third and the 4th carbon, there were methyl groups on the 3rd and 7th Carbon.

Therefore 3,7-dimethyloct-3-ene
16. (Original post by super121)
I know that. I did the Mr of 2 NaCl (117 I think). (200000/117)/2 to get moles of Cl2 them multiplied that by 24.

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Did you get 41025 or around that?

You didn't need to multiply the Mr of NaCl by 2!
17. (Original post by ambbs)
Anyone else hate that last 6 mark question on the advance notice? Thought the paper was going alright up until I got to that question, I didn't have a clue!

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I thought it was a nice 6-marker. The answers are mainly on the bottom right paragraph of page 3, with some of the equations already there. I talked about how N2O can be broken down in the atmosphere by high frequency/energy UV radiation, giving the N2O -> N2 + O equation. Plus N2O itself can react with existing oxygen radicals in the atmosphere, so that may break it down also...

I'm sure you would've picked up marks
18. (Original post by Davelittle)
Did you get 41025 or around that?

You didn't need to multiply the Mr of NaCl by 2!
No, I got half of that so will probs just lose a mark as they have efc

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19. what was the answer for the ppm to % questionhoiw many times larger was it???I got 7.8i think its wrong
20. (Original post by Jooost)
what was the answer for the ppm to % questionhoiw many times larger was it???I got 7.8i think its wrong
780 000 000 or something along those lines

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