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# AQA AS Chemistry unit 1 resit May 27th 2016 Watch

1. (Original post by Bailey2j09)
This was the one where you had to convert m3 into dm3 right?
yeah you converted it by x1000 right?
2. Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 23:8 but i forgot to write the formula, so how many marks do you think i will lose :'(
3. (Original post by Ultracrepidarian)
i think i got 0.113 m3 , and then got 80kg for the mass
Mass I got 1065000g as well and 0.113m3
4. (Original post by riixx)
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 23:8 but i forgot to write the formula, so how many marks do you think i will lose :'(
probably just one mark lost
5. (Original post by Ultracrepidarian)
yeah you converted it by x1000 right?
yeah making 3,000 dm3
then you found moles of one and it was a 4:1 ratio so you had to divide the mass by 4 then use those moles to find mass
6. (Original post by riixx)
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 23:8 but i forgot to write the formula, so how many marks do you think i will lose :'(
Should just be one
7. (Original post by Bailey2j09)
yeah making 3,000 dm3
then you found moles of one and it was a 4:1 ratio so you had to divide the mass by 4 then use those moles to find mass
i got 3000dm3 then x by 5 as that was the conc to get moles then i divided by 4 and then x by the mr to get mass
8. (Original post by riixx)
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 23:8 but i forgot to write the formula, so how many marks do you think i will lose :'(
Probably only 1 as the bulk of the question was in the calculation
9. Also for the mass spectra question i wrote similar relative abundance because they produce peaks at the same position of abundance on the mass spectrum and difference was different m/z value because 2+ ions is formed as 2 electrons could be knocked out due to more ionisation
10. (Original post by selena0101)
What did u guys get for why do vdw forces exist
induced dipoles are constantly being created and eliminated which attracts molecule together
11. (Original post by 78Saab)
I reckon 54-55, this paper wasn't THAT easy.

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Agreed
12. (Original post by Ultracrepidarian)
i got 3000dm3 then x by 5 as that was the conc to get moles then i divided by 4 and then x by the mr to get mass
yeah thats what i did
13. (Original post by Bailey2j09)
yeah thats what i did
what mr did you use do you remember what it was
14. I'm guessing grade boundaries will be A-56,B-49
15. Anyone here doing CHEM2 as well?
16. (Original post by Kattkin)
How the hell did I get 16% for percentage yield... Fml
I got the complete wrong answer for that aswell. never mind
17. For the VDW forces questions can you say there was a difference in electronegativity so a instantaneous dipole formed causing weak intermolecular forces between molecules
18. (Original post by A2LEVELSHELPME)
Anyone here doing CHEM2 as well?
yes
19. (Original post by Kattkin)
How the hell did I get 16% for percentage yield... Fml
i too got that we worked out atom economy instead of yield percentage
20. (Original post by Ultracrepidarian)
how did you work it out i got 80 something kg
The conc & vol of the solution was 5moldm-3 & 3m3, You had to change the 3m3 into dm3 first so you ended up with 3000dm3

moles = conc X vol = 5*3000 = 15,000 moles h3po4

Ratio P4O10 to H3PO4 was 1:4 therefore 15000 moles h3po4 = 3750 moles P4O10

Mass = moles * mr = 3750 * ((31*4)+(10*16)) = 1065000g = 1065KG.

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