2016 A Level H2 Chemistry Paper 2, 3, 1 discussions

last SG · 2016-11-08T20:10:45+00:00

I would think they should accept only NO2+S02=SO3+NO then regeneration bla bla blaso its like a homogeneous catalyst and Oxidising agent i would think elect...

Thefire521 SG

Manageable. Indeed ridiculously easy but many to trick students. Including the copper question

Thomas00 SG

Yeah, i got tricked by the copper question. Will Ultima be posting the ans? Or Fire.

Thefire521 SG

Give me a second. I need to get home. If u guys have any q for discussion u can ask first. Dont worry if u have some wrongm above 35 is safe enough regardless of bells

Hi answers as follows. please say if you disagree.

BDCDACCDBDCACBDAAADDBBBADCABBBBACDCBCBAC

Are there any typos?

seems like cambridge like to repeat letters thsi year. so those people who anyhow guess random letter will ...

James Pek SG

Hi answers as follows. please say if you disagree.

BDCDACCDBDCACBDAAADDBBCADCABBBBACDCBCBAC

Are there any typos?

23 is a C or?

UltimaOnline SG

Hi answers as follows. please say if you disagree.

BDCDACCDBDCACBDAAADDBBCADCABBBBACDCBCBAC

Are there any typos?

Agree with you for all answers except Q23. The atoms in propyne are s-sp-sp-sp3.

Thomas00 SG

My Q23 is B, and my Q38 is A.

captainkidzs SG

23 is definitely be. there isn't any sp2 carbon

HardcoreBubbles SG

My Q23 is B, and my Q38 is A.

Q23 is B too, Q38 option 3 is wrong as it should be a negative not positive charge i think?

For qn 11, Ag+ is reduced and Fe2+ is oxidized right? Hence to make it more negative shouldn't it be 'more' oxidation thus increase Fe2+ concentration (B) not C?

fluxboy98 SG

Does anyone here have the h1 chem p1 answers?

captainkidzs SG

but if u increase option c, equilibrium will cause Eo value to shift to make-0.77 more negative. so it can be 0.00

Thomas00 SG

Q23 is B too, Q38 option 3 is wrong as it should be a negative not positive charge i think?

For qn 11, Ag+ is reduced and Fe2+ is oxidized right? Hence to make it more negative shouldn't it be 'more' oxidation thus increase Fe2+ concentration (B) not C?

Ah i see, thanks.

For Qn 11,

Ag+ is reduced, Fe2+ oxidised.

Ecell = Red - Oxid

= 0.80-0.77

U want to make it 0, so have to increase 0.77 to 0.80, so increase Fe3+ can increase 0.77V to 0.80V. I think

Guys, how come Q22 not C.

Alex001 SG

What's the usual mark people get for SPA? I heard that the mark is often overestimated.

HardcoreBubbles SG

Guys, how come Q22 not C.

i still don't get Q11- wouldn't increasing Fe3+ conc mean POE shifts right meaning that there's decreased oxid so Eoxid becomes less negative? so Ecell becomes more positive? @[email protected]

i think bc you want only 1 full product, so your original atoms from PtCl4 must all be there.

captainkidzs SG

Ah i see, thanks.

For Qn 11,

Ag+ is reduced, Fe2+ oxidised.

Ecell = Red - Oxid

= 0.80-0.77

U want to make it 0, so have to increase 0.77 to 0.80, so increase Fe3+ can increase 0.77V to 0.80V.

It's because not all the cl will be removed. so it forms pt (nh3)4cl2 which form ionic bonds with 2 chloride ions Qn 7 I got 114. Anyone can show me how to get 117?

Skyrev SG

Why is the oxidation state of Vanadium not +4?

DemonicTable SG

It's because not all the cl will be removed. so it forms pt (nh3)4cl2 which form ionic bonds with 2 chloride ions Qn 7 I got 114. Anyone can show me how to get 117?

I suspect you used 76cm^3 instead of 78cm^3.

EDIT: Thanks @HardcoreBubbles for pointing out typo. You used 78cm^3 instead of 76cm^3.

captainkidzs SG

@ Thomas because not all chlorine will be removed. so it should form pt (nh3)4cl2 which goes on to form ionic bonds with 2 chloride ions.

I got option B for qn 7.

@sky because if u look at the data booklet, the product is the reactants for the reaction just above it. and Eo is still positive so it should form v2+

HardcoreBubbles SG

DemonicTable mixed it up: you used 78 instead of 76. Initial reading was 2!

captainkidzs SG

but don't u need to consider that the initial reading was 2? and the liquid should be 76 since u subtract the difference to get the amount of liquid

Thomas00 SG

i still don't get Q11- wouldn't increasing Fe3+ conc mean POE shifts right meaning that there's decreased oxid so Eoxid becomes less negative? so Ecell becomes more positive? @[email protected]

i think bc you want only 1 full product, so your original atoms from PtCl4 must all be there.

By looking at Fe3+ + e -> Fe2+

Increase in Fe3+ will cause +0.77V to become more positive.

Then you factor in the equation

Ecell = Ered - Eoxd

Original Ecell = +0.80V - (+0.77V)

New Ecell [After adding Fe3+] = +0.80V-(+0.80V) = 0

I'm not sure if this is the right explanation, but thats how i do it :)

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