The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

AQA AS Chemistry unit 1 resit May 27th 2016

Scroll to see replies

Original post by Bailey2j09
This was the one where you had to convert m3 into dm3 right?


yeah you converted it by x1000 right?
Reply 241
Avatar for riixx
riixx
1
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 2:2:3:8 but i forgot to write the formula, so how many marks do you think i will lose :'(
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
Original post by riixx
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 2:2:3:8 but i forgot to write the formula, so how many marks do you think i will lose :'(


probably just one mark lost
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
Original post by riixx
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 2:2:3:8 but i forgot to write the formula, so how many marks do you think i will lose :'(


Should just be one
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
Original post by riixx
Okay guys i made a stupid mistake. For the empirical formula i wrote the ratio which was 2:2:3:8 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
Reply 248
Avatar for riixx
riixx
1
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
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 :smile:
Original post by 78Saab
I reckon 54-55, this paper wasn't THAT easy.

Posted from TSR Mobile


Agreed
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
Original post by Bailey2j09
yeah thats what i did


what mr did you use do you remember what it was
I'm guessing grade boundaries will be A-56,B-49
Anyone here doing CHEM2 as well?
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 :frown:
Reply 256
Avatar for riixx
riixx
1
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
Original post by A2LEVELSHELPME
Anyone here doing CHEM2 as well?


yes
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
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.

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you