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...

ArJoe SG

Last Q5 should be oxidative cleavage, PCL5s RT for steps 1 and 2

but your second one should not be using Br2 because you will get disub

But do i get marks for writing correct reagent in step 4?

Jlptj SG

Hi what is the answer for the energy cycle qn? Just wanna see if i got it correct

Thefire521 SG

Hi for the last question, it is acidified kmno4, dry pcl5
then the second one is liquid bromine, excess concentrated nh3, heat in a sealed tube?

And for qn 3 the deduction, is it geometrical isomer and 4 isomers?

ArJoe SG

Your part b i answer would have been wrong. part b ii was on entropy so its unrelated.

Do you get any method marks for writing correct values and cycle, but just arrows in the opposite direction?

UltimaOnline SG

Thanks TheFire521, for helping out the students with their queries, I'll leave it to your good hands :)

Q3. Both optical isomerism / enantiomerism, *and* geometrical isomerism / cis-trans / E-Z isomerism. Hence total stereoisomers = 2^2 = 4.

Thefire521 SG

Hi what is the answer for the energy cycle qn? Just wanna see if i got it correct

For energy cycle

1). Did you times the enthalpy change of formation by 2 if you used the equation given

2). Did you times the vaporisation enthalpy by 2 if you used the equation given

3). Was your bond energy arrow in the correct direction (so you get a positive value at the end)-using a negative arrow means you dont understand the definition of bond energy-of course lose marks, but they will give you marks for knowing how to apply your cycle to your final answer

4). Did you include the bond breaking energies for Br2 and 3F2 from the data booklet?

UltimaOnline SG

Q3 for the last part people around me were telling me its structural isomers!

Q3(iii) refers to stereoisomers. Q3(iv) refers to structural isomers.

ArJoe SG

Hi why cant the last qn be disub? Since there are 2 acyl chloride groups… i am not very sure.. but i can still get marks for stating excess conc nh3 , heating in a sealed tube right?

Thefire521 SG

But do i get marks for writing correct reagent in step 4?

Of course the 7 marks are allocated for each reagent and each intermediate drawn correctly. So if you get 3/7 right then you get 3/7..

Thomas00 SG

Ultima, which questions u find more time consuming?

Is the percentage by mass 44%? And for the cell diagram is it O2 on one side and methane gas on the other?

UltimaOnline SG

Ultima, which questions u find more time consuming?

Is the percentage by mass 44%? And for the cell diagram is it O2 on one side and methane gas on the other?

Q1 & Q3.

Yes (but you should give to 3 sig fig) and yes (labeled with standard pressures of 1 bar or 1 atm).

ArJoe SG

Hi just asking for qn 5 will there be ecf? So if i used disubstituted bromine and disubstituted amine in the next product, will they mark the amine part correct?

Thomas00 SG

Q1 & Q3.

Yes (but you should give to 3 sig fig) and yes (labeled with standard pressures of 1 bar or 1 atm).

Ok thanks :)

UltimaOnline SG

Hi just asking for qn 5 will there be ecf? So if i used disubstituted bromine and disubstituted amine in the next product, will they mark the amine part correct?

No guarantees. For purpose of estimating your own marks, better play safe and assume no error carried forward.

ArJoe SG

No guarantees. For purpose of estimating your own marks, better play safe and assume no error carried forward.

For the energy cycle question, if you sub in all the correct values, correct substances, butyou drew bond energy arrow in the opposite direction, how many marks can be awarded?

UltimaOnline SG

For the energy cycle question, if you sub in all the correct values, correct substances, butyou drew bond energy arrow in the opposite direction, how many marks can be awarded?

For purpose of estimating your own marks, better play safe and assume 2 out of 4 marks.

UltimaOnline SG

Gonna be away-from-keyboard for next few hours. U guys carry on discussing amongst urselves.

theophilus SG

Anyone managed to find K for question 3 ? K was damn hard to find

Nomkla SG

Anyone managed to find K for question 3 ? K was damn hard to find

If i am not wrong, theres intramolecular bonding which would consist of the double bonds needed to form H

Thefire521 SG

Ultima, which questions u find more time consuming?

Is the percentage by mass 44%? And for the cell diagram is it O2 on one side and methane gas on the other?

I would think the CO2 should be a gas also. some people might choose to dissolve it in aqueous just like your coke but co2 should not be able to dissolve to hit 1moldm3

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