Chemistry Examination Discussion

[Edward21]

Half of me is like omg as if you did all those practice exams preparing for harder stuff but hey, easy exam or hard we all have to prepare as best as we can for both. Though that copper electrorefining is driving me crazy. Hopefully I can get 2/3 or 3/4 whatever it was for getting an answer of like 12% 

[radl223]

For the days question i also got 12 point something days and i put my final answer to 13 days, would I still get a mark for that? Since I believe that it was to two sig figs (due to given amp) and the fact that rounding down would neglect the rest of the point something.

[achre]

Anyone remember the polarity of the impure copper electrode?

[simba]

Anyone remember the polarity of the impure copper electrode?

I said positive

[Edward21]

I said positive

I forgot about electrorefining, but once I saw that the impure copper lost mass I was like omg anode, positive in electrolysis!

[achre]

I said positive

Oh thank god.

[Chazef]

I just thought 'if the pure copper electrode is getting plated, it's gotta be receiving electrons to give to cations in the electrolyte so it's the cathode and it's electrolysis so the anode doesn't really want to be giving electrons so it's positive'

[eddybaha]

i dont get why the percentage purity question was 4 marks. isnt it just mass gained by pure copper electrode divided by original mass of impure copper?

[Edward21]

i dont get why the percentage purity question was 4 marks. isnt it just mass gained by pure copper electrode divided by original mass of impure copper?

That's what I was thinking exactly, then I realised this was that hard question on the paper, I changed my mode of thinking and went really technical to get about 12ish percent (probably wrong) just because it seemed wayyy too simple for 3 or 4 marks.

[melbourene95]

i always got 12 days

quite disappointed with how simple the exam was considering the study i put in

[simba]

That's what I was thinking exactly, then I realised this was that hard question on the paper, I changed my mode of thinking and went really technical to get about 12ish percent (probably wrong) just because it seemed wayyy too simple for 3 or 4 marks.

I thought it was worth too much, but then I realised those 4 marks were for two parts (it was also for an explanation as to why the masses could be incorrect) So the calculation part would only be 2-3 marks

[Edward21]

i always got 12 days

quite disappointed with how simple the exam was considering the study i put in

Yeah, I knew it all inside out, the really fine bits including avogadro's number determination and all the fine bits of mass spec; then to get an example of oh the C NMR has 4 peaks, there are 4 carbon environments in the ester. I guess it's the burden of the new exam format? They could definitely do a harder one next year.

[melbourene95]

Yeah, I knew it all inside out, the really fine bits including avogadro's number determination and all the fine bits of mass spec; then to get an example of oh the C NMR has 4 peaks, there are 4 carbon environments in the ester. I guess it's the burden of the new exam format? They could definitely do a harder one next year.

next year will probably quite challenging.. it wasn't even that lengthy!

[Mafioso]

i always got 12 days

quite disappointed with how simple the exam was considering the study i put in

LOL I forgot to convert the kg to g when working out mol and therefore got like 0.012 days All my calculations were right except it was expressed in g. Reckon I'll only lose 1 mark for this?

[Edward21]

With a reason of why the electrolysis or refining of copper may not be accurate, do you reckon this would be accepted: I mentioned molarity of the solution, if the H+ is too high > 1M (non-standard) it could be reduced to H2 preferentially instead of Cu2+... it was the best I could do haha. It's like how electrolysis of brine 4.0M NaCl produces Cl2; do you reckon my conclusion is reasonable?