Chemistry Examination Discussion

[achre]

Does anyone know the exact wording of that copper refining question?
If I remember correctly, didn't it ask for a reason for having different values for the mass of the copper plate after the electrolysis?
I think I may have thought too simply when I said it may not have been completely dry when weighed. 

The question asked what possible sources of inaccuracy there could be. I said that there could be cations present in the solution that would be reduced preferentially to copper that would contribute to the mass of the plate. Thinking back on it, I should have been more specific with the species... but all we know is that there were 'impurities' on the other electrode, and it was worth one mark, so that should be okay, right?

[rany]

For that accuracy question I said that one factor could be the voltage of the DC supply but didn't really elaborate, can that get a mark still? because the question didnt say explain it just said STATE one factor.

[presto]

The question asked what possible sources of inaccuracy there could be. I said that there could be cations present in the solution that would be reduced preferentially to copper that would contribute to the mass of the plate. Thinking back on it, I should have been more specific with the species... but all we know is that there were 'impurities' on the other electrode, and it was worth one mark, so that should be okay, right?

Yeah, I think your answer is fine.
Would my response about it not being weighed properly be accepted? It is still a source of inaccuracy... right?

[Edward21]

For that accuracy question I said that one factor could be the voltage of the DC supply but didn't really elaborate, can that get a mark still? because the question didnt say explain it just said STATE one factor.

I know VCAA exams say "State" however if there's space I will explain!

[beastly101]

Anyone get the structure

CH3CHCH3COOH for the isomer of ethyl ethanoate that the chemist was suggesting it was?

[Dayman]

I think it was HOCH2CH(CH3)CH2OH I might be wrong it's the last one I did.

[brightsky]

Anyone get the structure

CH3CHCH3COOH for the isomer of ethyl ethanoate that the chemist was suggesting it was?

looks good.

[beastly101]

I think it was HOCH2CH(CH3)CH2OH I might be wrong it's the last one I did.

The formula was C4H8O2 though I think..

[Scooby]

Anyone get the structure

CH3CHCH3COOH for the isomer of ethyl ethanoate that the chemist was suggesting it was?

yup

[simba]

I thought there were meant to be three different carbon environments?

[beastly101]

I thought there were meant to be three different carbon environments?

Yeah, there was, but the CH3 groups are equivalent carbon environments so there is three for CH3CHCH3COOH

[hurdles]

The CH3 groups are not equivalent

[Edward21]

Umm I don't understand semi-structurals that well, was it this? Methylpropanoic acid?

[Mafioso]

Umm I don't understand semi-structurals that well, was it this? Methylpropanoic acid?

Yep exactly this.

[beastly101]

Umm I don't understand semi-structurals that well, was it this? Methylpropanoic acid?

Yep, I had that.