ATARNotes Official Solutions to VCAA 2012 Unit 4 Chemistry Examination

[thushan]

Here you go!

If there are any issues, please post

[Tonychet2]

out come the undisputable solutions ... TY!

[thushan]

out come the undisputable solutions ... TY!

LOL nah man, if there are mistakes, tell me

[thetimeis]

Q2Bii)
Didnt even look at the diagram for activation energy, but said the reaction in step 2 was exothermic so would release energy- increasing temperature of its direct surroundings causing reaction rate to increase (so the other one was slower). Yay or nay?

[thushan]

:/ I don't think they'd pay that sorry

[rebeccab26]

you are a genius
i messed up a few things but its okay what's done is done

thanks for that thushan

[joseph95]

2.b.ii) I wrote what you wrote but then crossed it out, and changed it to say that Step 2 would have a higher rate because the reaction is exothermic, with the temperature increasing from the release of energy, which then increases the rate by increasing the kinetic energy of the particles. Thus step 1 is slower as it is an endothermic reaction and the temperature decreases.

What do you reckon?

Edit: I just realised someone else asked this. I just thought it'd be weird to say it's because of the activation energy.

[dfgjgddjidfg]

for the Ka value i simply wrote its diprotic would i get a mark. for the 1.a i wrote the rate at which co2 is bubbling out of solution,for 3.a i wrote an acid that partially ionises for 3.bii i did 2- instead of two -, 6.b loss of heat to the environment, would i get marks for any of them?

[thushan]

I'd accept 'diprotic acid'

CO2 bubbling out of solution...it's not very quantitative...0.5/1 (one examiner might pay it, another might not)

an acid that partially ionises - 0.75/1 (as in most examiners probably would pay it, but you might have some ass examiner who won't)

3bii. :/ i don't think so, unless you wrote the molecular formula of the ion

6b. that's fine!

[baddin]

Hey would this be acceptable: HOOCCH2CH(OH)COO- + H20 -> OOCCH2CH(H)COO2- + H3O+ for 3.b)ii)

[thushan]

:/ sorry...that notation isn't right

[FlorianK]

oh for 6b) I thought they wanted you to say that the calculated value was the enthalpy for the combustion for 2 mols of methanol
I guess that was too much of a troll answer

[thushan]

Actually, that's what I was going to put originally! But then I saw that it was worded differently.

[baddin]

Also for Q6. b) can i write "Side reactions could affect the delta H value".

[datfatcat]

What if I wrote the size of CaCO3 (in lump or powder) for q1bi? No mark?

And q3a) acids that are not fully ionised in water? any mark?