Suggested Solutions - DONE

[username]

Could you have written lack of standard conditions or something really vague like that for the methanol question, 6bii?

Actually that's probably the safest answer...instead of what I wrote (gaseous CO2 escapes => less methanol than expected produced)

Oh that's a relief. But its okay, you aced it anyway, unlike I did.

[Synesthetic]

Could you have written lack of standard conditions or something really vague like that for the methanol question, 6bii?

Actually that's probably the safest answer...instead of what I wrote (gaseous CO2 escapes => less methanol than expected produced)

Oh that's a relief. But its okay, you aced it anyway, unlike I did.

I lost 9 marks, I hardly aced it

If 87% is the cut-off for A+ again I might get a score in the low 40's, though.

[ilovevce]

Hmm, for the methanol question, couldn't the reason be that some water would be electrolysed, hence reducing the amount of methanol electrolysed. It is quite possible that a small amount of water would be electrolysed.

Also, for the disposal question in MC, did it say NaCl? I thought it said unused NaOH.

[charm]

Also, for the disposal question in MC, did it say NaCl? I thought it said unused NaOH.

it said NaCl im pretty sure...

[username]

Could you have written lack of standard conditions or something really vague like that for the methanol question, 6bii?

Actually that's probably the safest answer...instead of what I wrote (gaseous CO2 escapes => less methanol than expected produced)

Oh that's a relief. But its okay, you aced it anyway, unlike I did.

I lost 9 marks, I hardly aced it

If 87% is the cut-off for A+ again I might get a score in the low 40's, though.

Don't worry, I know you'll get >40s ^_^. Goodluck.

[julezian]

fuck this shit lol
there goes my 40

[hamtarofreak]

Thanksyuu for putting these up Mao, you're a legend. =)

I did pretty good in the end it seems. See, it does pay to neglect Chemistry. =P

[lanvins]

For an advantage of a fuel cell would it be acceptable to say becuase it supplies a continuous supply of electricty as long as a continous supply of reactants is provided or was it necessary to make a comparison?

[ed_saifa]

See, it does pay to neglect Chemistry. =P

My Chem teacher would strike you down for saying that

[hamtarofreak]

See, it does pay to neglect Chemistry. =P

My Chem teacher would strike you down for saying that

Yeah lol, my Chem teacher gave me the coldest look when I said I'd studied for every exam but my 2 today =P

[Synesthetic]

For an advantage of a fuel cell would it be acceptable to say becuase it supplies a continuous supply of electricty as long as a continous supply of reactants is provided or was it necessary to make a comparison?

The comparison is somewhat implied here. I would accept that...

[pfftlah]

Synesthetic: i got the same answers as you regarding the change in pH and oxygen being the only reactant [the answers you had different to mao's]. i doubt that we were required to think that in depth for the pH question - if they had wanted us to consider the relative weakness and strength of the acids, they would have guided us through it and it would have been worth more than 2 marks.
im quite happy, i think i can get an A+ [hopefully!] does anyone remember for MC question 8 which graph had the curved lines rather than the straight ones? i think it was D..damn i think i got that wrong.
is incomplete reaction a suitable answer to the lower methanol output?
thanks mao and synesthetic for putting up the answers.
yaaaaaaaaaaaaaaaay, FREEDOM =D
we can enjoy ourselves without feeling guilty now [well for those of us who've finished exams that is]

[Synesthetic]

Synesthetic: i got the same answers as you regarding the change in pH and oxygen being the only reactant [the answers you had different to mao's]. i doubt that we were required to think that in depth for the pH question - if they had wanted us to consider the relative weakness and strength of the acids, they would have guided us through it and it would have been worth more than 2 marks.
im quite happy, i think i can get an A+ [hopefully!] does anyone remember for MC question 8 which graph had the curved lines rather than the straight ones? i think it was D..damn i think i got that wrong.
is incomplete reaction a suitable answer to the lower methanol output?
thanks mao and synesthetic for putting up the answers.
yaaaaaaaaaaaaaaaay, FREEDOM =D
we can enjoy ourselves without feeling guilty now [well for those of us who've finished exams that is]

Well it's somewhat a relief to know that I was not the only one

I'm hoping you are right about the change in pH, as I said before it seems unreasonable for - as you mentioned - a 2 mark question. Still would rather have known about Mao's answer, that way you cannot be penalized.

Quite a few people I know also only chose O2, as we did - I think my problem was that I was too fixated on the materials for the Contact Process, rather than industrial production on a broader scale. But that question was farcical, we spent the entire year learning about the equilibrium considerations of the converter reaction and all we needed for the exam was a reaction above room temperature!

Yeah incomplete reaction might be acceptable, especially if there were stoichiometric considerations in the question parts beforehand (can't recall...) I really can't give a more definite answer! But I will maintain that username's answer - absence of standard conditions - is probably the safest answer, given that it is an electrolytic reaction. Although the only problem with that is the methanol synthesis reaction is not in the assigned electrochemical series....but it shouldn't really matter.

And yes MC #8 the graph with curved lines was D, I chose it too and felt like an idiot when I read his solutions

[Synesthetic]

c) In the converter, heated gas is recycled between runs through catalyst beds, hence reducing heating (energy) costs

Hmm, perhaps this was not as far off the mark as I thought...

"To conserve energy, the mixture is heated by exhaust gases from the catalytic converter by heat exchangers."
[ http://en.wikipedia.org/wiki/Contact_process ]

And well, in this following image these heat exchangers seem to facilitate my 'runs through catalyst beds'
[ http://media-2.web.britannica.com/eb-media/59/7359-004-224E8A41.gif ]

Not an identical response but it makes me feel a whole lot better, I thought I had totally stuffed that one by conflating considerations for the exothermic reaction with the double absorption process

*edit* regarding, 5)a) circling O2 and (?) FeS2
"During WWII...The sulfur [from iron sulfide] was used in the production of sulfuric acid, an important chemical for industrial purposes. Now most sulfur production comes from H2S gas recovered from natural gas wells."
[ http://mineral.galleries.com/minerals/sulfides/pyrite/pyrite.htm ]

A bit out of date, VCAA; I thought the whole coursework was engineered towards rendering students as MODERN chemists Maybe there were testing us on our knowledge of the chronology of the industrial chemical age...

[jeremykleeman]

Hey for the methanol one, I wasn't sure but it said in the previous question to assume all charge is converted. I was going to write something like loss of energy in the wire, but I thought that would contradict the previous question so i just said that methanol might react with something or some may evolve as gas. Probably wrong...

I did the same pH calculation as you guys (same change), but Mao raised doubts in me. Ignoring the fact it is a weak acid and just given the pH of solution I think we would be right, but now I am not sure.

Good luck to everyone with your study scores!