Can someone please please please help me in this ALEVEL CHEM pp question ?

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Leah.J
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#1
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Q14 part b ii
https://qualifications.pearson.com/c...e_20180119.pdf

https://qualifications.pearson.com/c...s_20180308.pdf

I got the ratio 1:4 which is correct according to the MS but I don't understand how we should know that the product is SO4 2-

I wrote the equation with S4O6 2- as the product because that was the product in part i , the ratio turned out to be 1:2 in my equation, which didn't match the calculation I made but how do I know whether my calculation is incorrect or my equation is incorrect in an exam ? Most importantly, how do I know what the products are when there are so many possibilities ?
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username3249896
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Br2 is a stronger oxidant than I2 so you might expect S to be oxidised more than +2 to +2.5

mole ratio of S2O32-:Br2 = 1:4
8 electrons are gained by the 4 Br2 molecules
this must be lost by 1 S2O32- molecule
each S atom must lose 4 electrons
Oxidation number of S must go from +2 to +6, so SO42- ion is formed
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Leah.J
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(Original post by BobbJo)
Br2 is a stronger oxidant than I2 so you might expect S to be oxidised more than +2 to +2.5

mole ratio of S2O32-:Br2 = 1:4
8 electrons are gained by the 4 Br2 molecules
this must be lost by 1 S2O32- molecule
each S atom must lose 4 electrons
Oxidation number of S must go from +2 to +6, so SO42- ion is formed
Oh, that makes sense.
1 more thing please, if a molecule had a C=C and an OH + a COOH
so
it was able to from both addition and condensation polymerisation, which one is more likely ?
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username3249896
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(Original post by Leah.J)
Oh, that makes sense.
1 more thing please, if a molecule had a C=C and an OH + a COOH
so
it was able to from both addition and condensation polymerisation, which one is more likely ?
Is it a past paper question? Any source?

Probably condensation polymerisation since small molecules are eliminated, hence giving a larger increase in entropy than the corresponding addition polymer of similar length
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Leah.J
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#5
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(Original post by BobbJo)
Is it a past paper question? Any source?

Probably condensation polymerisation since small molecules are eliminated, hence giving a larger increase in entropy than the corresponding addition polymer of similar length
No, I just saw the polymer polypropenamide and I got the question. It can't form condensation polymers I know
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