Exam predictions

[Richiie]

Think it's mostly organic.

[Greggler]

It wont get any harder i dont think from last year, maybe a random question here or there in SA worth a mark or two on theory that might throw some people and a few dodgy MC's.

But im pretty sure the some where in last years assessors report in said that the examiners were 'happy' with the standard of difficulty and that it was a 'challenging exam'.

[Potter]

It wont get any harder i dont think from last year, maybe a random question here or there in SA worth a mark or two on theory that might throw some people and a few dodgy MC's.

But im pretty sure the some where in last years assessors report in said that the examiners were 'happy' with the standard of difficulty and that it was a 'challenging exam'.

With all due respect, I think that's the examiners egos talking.

[azn_dj]

Im predicting Ethanol to Ethanoic acid, using Potassium Dichromate or Permanganate.
At least there is one less short answer question in this year's exam.
Density included.

Also ethanol being combusted. This is probably where states mark is hidden.

[chansthename]

huh, what are you talking about?

http://www.vcaa.vic.edu.au/vcaa/vce/exams/examcovers/June_2010_covers/2010chem1-cover.pdf

From a left hand perspective, so the phosphate and deoxyribose is on the left (I just prefer it on the left)

[kyzoo]

Im predicting Ethanol to Ethanoic acid, using Potassium Dichromate or Permanganate.
At least there is one less short answer question in this year's exam.
Density included.

Also ethanol being combusted. This is probably where states mark is hidden.

Is this C2H5OH (g) + O2(g) --> 2CO2 (g) + 3H2O(g)

[Martoman]

Any alcohol is a liquid.

[kyzoo]

Lol assessor's report for Question 7a in VCAA 2008 said that (g) or (l) is acceptable for ethanol and water

[Martoman]

LAWL assessor needs to assess his marking schema.

[kyzoo]

=/ But ethanol is being combusted isn't it? Since ethanol has a low boiling point, isn't it a gas at the temperature of combustion?

[Martoman]

I concede your point.

Could be either

[stonecold]

I think that only hydrocarbons with only C and H are volatile at room temp, and they must be four carbons or less.

Alkanols, have the polar group, which means they can form h-bonds with other molecules, so generally require more than room temp to become gaseous.

Both (l) and (g) are right though.  It depends how you interpret the question.  Just before the reaction, ethanol will be gaseous, as it has been heated, however if you interpret before the experiment as in reactants sitting in their container, then it will be liquid.

[m@tty]

Combustion initially happens where the fuel is in the gas phase. Liquids only combust above their flash point. This is where there is enough evaporated fuel to start combustion. For ethanol this is 12.8[sup]o[/sup]C, so it will still mostly be liquid. But you can argue that the actual combustion is with gaseous ethanol.

Though if there is no spark or source of energy to initiate the reaction then the autoignition temperature must be reached. For ethanol this is 365[sup]o[/sup]C I think you'll agree that it will be a gas here.

So yeah, either can be argued.

[Martoman]

I reckon there will be a question asking:

Spell electrophoresis: _________________________             1 mark.



Examiners report: Many students found this difficult, mainly because they thought it was a trick question.

[kyzoo]

I have 2 questions

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1. VCAA 2008 Sample Paper Question

Prior to the experiment, the concentration of the NaOH was experimentally determined by titrating the NaOH against a standard solution of HCl. Suppose about 10mL of the HCl were spilt on the floor during the experiment. How would you safely neutralize the spill

~ Can you say "Add diluted solution of NaOH(aq) to the spill"?

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2. I'm confused about the use of states in "reaction pathways reactions." According to assessor's report for VCAA 2007 Question 5c, you don't have to use states if you use the semistructural formula of the organic compounds involved???