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AS Chemistry 2016 Unofficial Mark scheme

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Original post by GabbytheGreek_48
if i remember in the question they said the isotopes were in equal abundances


It is still three peaks because it could be 79-79 , 79-81, 81-81
Original post by GabbytheGreek_48
if i remember in the question they said the isotopes were in equal abundances




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1464352023533.jpg49.8KB
Original post by DaVinciGirl


oh crap yeah that makes sense
Original post by DaVinciGirl
What type of bonding was it between Aluminium and Nitrogen? Was it dative?

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Yeah it was
Original post by sharmonraja
Ohh okay, and what about the reducing agent, C2O4 or Cr2O7 ?


I don't exactly remember the equation but a reducing agent is oxidised so I cancelled out H+ and another cation as a possibility and Cr2O7 has a positive +3 which turns into 0 when it forms a sulphate (precipitate) , although I'm not entirely sure.
Original post by DaVinciGirl
I got 2ClO- + 4H+ + 2e- --> Cl2 + 2H2O

Overall
2ClO- + 4H+ + 2Cl- --> 2Cl2 + 2H2O
( not sure if this is right though )

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I got the same !! But for the overall equation I didn't write an ionic equation so mine was
2HClO + 2HCl ---> 2Cl2 + 2H2O
Original post by sharmonraja
I got the same !! But for the overall equation I didn't write an ionic equation so mine was
2HClO + 2HCl ---> 2Cl2 + 2H2O


That's probably right, I wasn't sure

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Cr207 any way is a oxidising agent to oxidise alcohol-> aldehydes -> carboxylic It cannot be a reducing agent hence the answer is c204
Original post by DaVinciGirl
That's probably right, I wasn't sure

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What did you get for the percentage of mass of MgCl2? (question before multiple choices)
And what did you get for the Mr of MHCO3?
149 for Mr and 35.4%

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Could some one remind me of the practical question- 6 marks
Was SiO2 a macromolecular?

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Yes

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Original post by skiichamp00
Cr207 any way is a oxidising agent to oxidise alcohol-> aldehydes -> carboxylic It cannot be a reducing agent hence the answer is c204


For organic the definition of oxidation and reduction slightly varies, oxidation being either adding oxygen or removing hydrogen and reduction is adding hydrogen or removing oxygen. Plus an oxidising agent in one reaction isn't always an oxidising agent in another.
What was the pv=nrt questions again ?
Reply 75
Avatar for marc_ken
marc_ken
Original post by DaVinciGirl
Was SiO2 a macromolecular?

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I didn't put that one think i put one with P something
Original post by marc_ken
I didn't put that one think i put one with P something


Anyone remembers the question about velocity? To find the mass is it just 52/Avogadro's number?
Reply 78
Avatar for elle.m
elle.m
7
1/L then x by Ar
I got 1714 ms^-1

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