VCAA Chemistry Examination - AN Official Solutions (Draft 1)

[charmanderp]

Frick this.

Haha mate don't worry, I'm sure your brain has been jellified by med exams in the last few days.

[simba]

also 10.bii, I think it should be 80O2, as there's the 6O atoms from the fatty acid

[thushan]

Yup I fixed that.

[thushan]

Yup I fixed that.

And looking at it again, I guess B would make more sense if you looked at the organic compound itself.

[simba]

Yup I fixed that.

Oh someone already mentioned it *derp*
I think this little lion needs some sleeeep

[Sergy01]

Is there meant to be a negative sign for the ∆H value in question 10, since it's combustion?

[saedf]

Your MC answers are scaring me :(

[thushan]

Is there meant to be a negative sign for the ∆H value in question 10, since it's combustion?

That too.

[bubblecups1]

Also, the number of moles of O2 excess is 0.061moles not the original amount in 8aii?

[thushan]

Oh, I just took it to mean how much of the reactant in excess there is originally.

Guys, I'm sorry from all the mistakes, I've just been extremely tired, I was under the pump these last two weeks with exam prep (and 2nd year med has pretty crazy exam prep with big exams and that ). I just finished today.

[Sentar]

For question 9 is it possible to say
Mass spectrum
Molecular ion peak at 88, same mass as CH3COOCH2CH3

Infared
Absorbtion band at 1750, meaning a C=O bond

Proton NMR
3 hydrogen environments, which is true for CH3COOCH2CH3

Also with 7.b, even with the explanation I still don't get why the total mass is 10.3 not 9.445, is it because the sludge stays on the electrode? Because I don't believe it says it was done until no more copper was being deposited so there may have been copper still there, or am I missing the point?

[saraoj]

For question 4, doesn't a decreased volume cause a shift to the left and thus decreased hydrogen yield? (Question 4a ii)
For the next part (iii), would an increased temperature not decrease the reaction rate for Reaction 2 because it is exothermic and thus the back reaction (endothermic) is favoured?
Thanks!

[rany]

CH2CH2 should be accepted because there is only one place the double bond can be. Also for the precipitation reaction would they accept my water being on top of the arrow? Am i being pedantic?

[xenial]

I did the same as Sentar for question 9 - in retrospect, I should have written a bit more 

What do you think about the relative simplicity/brevity of those answers? (In your own opinion, of course)

[joey7]

I did the same as well! Surely they couldn't give you zero for those answers?