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    (Original post by Bailey2j09)
    This was the one where you had to convert m3 into dm3 right?
    yeah you converted it by x1000 right?
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    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 :'(
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    (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
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    (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
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    (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
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    (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
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    (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
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    (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
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    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
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    (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
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    (Original post by 78Saab)
    I reckon 54-55, this paper wasn't THAT easy.

    Posted from TSR Mobile
    Agreed
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    (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
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    (Original post by Bailey2j09)
    yeah thats what i did
    what mr did you use do you remember what it was
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    I'm guessing grade boundaries will be A-56,B-49
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    Anyone here doing CHEM2 as well?
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    (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
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    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
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    (Original post by A2LEVELSHELPME)
    Anyone here doing CHEM2 as well?
    yes
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    (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
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    (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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