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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: TrueTears on March 23, 2009, 06:13:00 pm

Title: Chemistry SAC question
Post by: TrueTears on March 23, 2009, 06:13:00 pm: I am just curious about a few things that happened today when we got our SACs back in class. Correct me if I am wrong but I think my friend was marked VERY harshly.

I will post the questions and what my friend wrote, please see if they were marked harshly.

1. Write the ionic equation for the reaction between ammonium sulfate and barium chloride. (worth 2 marks this question)

This is what my friend EXACTLY wrote:

$BaCl_2 (aq) + (NH_4)_2SO_4 (aq) -> BaSO_4 (s) + 2NH_4Cl (aq)$

$\implies Ba^{2+} + SO_4^{2-} -> BaSO_4$

Now the examiner said that because he wrote the FULL equation he lost 1 mark. I mean what the hell... he wrote the ionic equation at the end, that was just his working and he lost a mark for it????!!???

2. Find the mole of NaOH if the concentration of NaOH is 0.200M and the volume is 0.350L

$n(NaOH) = 0.2 \times 0.35 = 0.0700$ (3 s.f)

Now this question was worth ONE mark and he lost the entire mark because the examiner wrote "Your working must also be in 3 significant figures". I thought that only answers had to be put in the sig figs of the least accurate information, but also the working?!?!?!? wth....?

So I would like to know whether he was marked harshly, or was he marked fairly.

Thanks guys.
Title: Re: Chemistry SAC question
Post by: kurrymuncher on March 23, 2009, 06:15:13 pm: yeah I reckon that has been marked pretty harshly. Dont we only have to do sig figs at the end??
and one mark off for writing the full eqn, wtf, thats bullshit. I dont think they would do that in the exam.
Title: Re: Chemistry SAC question
Post by: jackinthepatch on March 23, 2009, 06:17:44 pm: yeah that's a massive load of bs
Title: Re: Chemistry SAC question
Post by: TrueTears on March 23, 2009, 06:19:07 pm: Yeah, so I was wondering should he go complain and get those 2 extra which I think he DESERVED to get...
Title: Re: Chemistry SAC question
Post by: kurrymuncher on March 23, 2009, 06:19:33 pm: yeah go complain and beat the shit out of that examiner!!
Title: Re: Chemistry SAC question
Post by: d0minicz on March 23, 2009, 06:59:53 pm: Did he include states on the ionic equation?
Title: Re: Chemistry SAC question
Post by: TrueTears on March 23, 2009, 07:01:29 pm: Quote from: d0minicz on March 23, 2009, 06:59:53 pm
Did he include states on the ionic equation?
yeah soz i left out that in my typing lol
Title: Re: Chemistry SAC question
Post by: shinny on March 23, 2009, 07:18:47 pm: The marker deserves to be shot. Neither of those 'errors' are even grey areas...you clearly do not need to maintain sig figs in working out (well as a matter of fact, it's actually wrong if you do?) and only the final line or whatever is indicated as the answer should be marked as the answer for a 1 marker.
Title: Re: Chemistry SAC question
Post by: Mao on March 23, 2009, 08:13:42 pm: That is unfair, but since this is a SAC, i wouldn't worry about it. Your relationship with your teacher is important in the final year, if you complain now and is determined to prove him/her 'wrong', life will just get more difficult for you. Take it as a warning, and maybe not be as big an ass in class [or whatever the cause of the problem is, the teacher clearly doesn't like this person], and be more careful next time. Two marks on a SAC isn't really THAT big a deal.
Title: Re: Chemistry SAC question
Post by: Over9000 on March 23, 2009, 08:16:29 pm: I think its marked by other teachers, not your specific teacher