ATAR Notes: Forum
Archived Discussion => 2012 => Mid-year exams => Results Discussion => Victoria => Chemistry Unit 3 => Topic started by: thushan on August 12, 2012, 09:16:22 pm
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Asking this on behalf of an acquaintance, but ppl who have statements - check what you got for the lead nitrate question (where you have to talk about its solubility). He's wondering whether you had to specifically quote 60g/100g in your answer.
Btw if that's the case, that's complete bs :P
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i started talking about general knowledge in how nitrates are all soluble then added the info given about the solubility. BTW what was question 3 as I lost 2 marks from it :( Anyway my answer was a mixture so i don't know if one would lose the mark.
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I definitely remember giving solubility as my reason but I didn't quote numbers and I lost the mark..
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Asking this on behalf of an acquaintance, but ppl who have statements - check what you got for the lead nitrate question (where you have to talk about its solubility). He's wondering whether you had to specifically quote 60g/100g in your answer.
Btw if that's the case, that's complete bs :P
I think I know said 'acquaintance' :P I didn't get a statement but my answer was 'There would be no precipitate to measure as nitrate ions are always soluble' or something along those lines, which I'm pretty sure I received a mark for given that I prolly lost 5 marks for careless errors and still got an A+, so I couldn't have lost too many more haha.
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According to my teacher (exam assessor), they gave a mark if you quoted the solubility from the data given OR said it was "very soluble", but not if you merely said that it was soluble. Because technically, iirc, nothing is ever truly insoluble, rather, there are degrees of solubility ranging from highly soluble to very poorly soluble.
There's that mark gone for me. :-\
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A more appropriate answer then would probably have been 'It cannot be measured as a precipitate is unlikely to form, given that nitrate ions are highly/almost completely/extremely soluble with all cations'. Drat.
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According to my teacher (exam assessor), they gave a mark if you quoted the solubility from the data given OR said it was "very soluble", but not if you merely said that it was soluble. Because technically, iirc, nothing is ever truly insoluble, rather, there are degrees of solubility ranging from highly soluble to very poorly soluble.
There's that mark gone for me. :-\
Drat!
Oh. I guess that's tight, very tight, but not dodgy. So something like "the solubility of lead nitrate is too high" would have been sufficient.