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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: melanie.dee on November 13, 2007, 04:04:58 pm

Title: drawing things
Post by: melanie.dee on November 13, 2007, 04:04:58 pm
what do we need to know how to draw off by heart?

like amino acids.. which ones?

do you need to be able to draw carbohydrates? glucose, fructose, and then disaccharides or anything like that? if so im fucked. haha.

anything else we need to be able to draw? especially in food chem?
Title: Re: drawing things
Post by: Daniel15 on November 13, 2007, 04:13:48 pm
Quote from: "melanie.dee"
do you need to be able to draw carbohydrates? glucose, fructose, and then disaccharides or anything like that? if so im fucked. haha.

However bad you are, I guarantee I'm worse  :lol:
I don't even know what a disaccharide is... Time to study I suppose  :shock:
Title: Re: drawing things
Post by: Ahmad on November 13, 2007, 04:19:09 pm
Quote from: "melanie.dee"
what do we need to know how to draw off by heart?

like amino acids.. which ones?

do you need to be able to draw carbohydrates? glucose, fructose, and then disaccharides or anything like that? if so im fucked. haha.

anything else we need to be able to draw? especially in food chem?


For carbohydrates I think only glucose. If they want you to draw fructose they'd give you extra information.
Title: drawing things
Post by: melanie.dee on November 13, 2007, 04:34:44 pm
eek i dont even know glucose atm. better get to studying. what about the amino acids?
Title: drawing things
Post by: principe on November 13, 2007, 04:57:01 pm
Quote from: "melanie.dee"
eek i dont even know glucose atm. better get to studying. what about the amino acids?

I haven't seen a question where they simply just ask you to draw an amino acid. But you should know at least the two to be safe. Glycine and Alanine are the easiest I think. There are questions that ask you to draw structural formulas of the reactants used to create a protein, so it shouldn't be a problem if you know how to break the peptide links.
Title: Re: drawing things
Post by: BA22 on November 13, 2007, 05:09:00 pm
Quote from: "melanie.dee"
what do we need to know how to draw off by heart?

like amino acids.. which ones?

do you need to be able to draw carbohydrates? glucose, fructose, and then disaccharides or anything like that? if so im fucked. haha.

anything else we need to be able to draw? especially in food chem?


glucose isn't too bad if you remember the formula
Title: drawing things
Post by: cara.mel on November 13, 2007, 05:16:01 pm
You need to know how to draw glycerol.

With everything else, they can give you 2 amino acids/monosaccharides etc and get you to join them together, or vice versa. You don't have to be able to do it by heart
Title: drawing things
Post by: BA22 on November 13, 2007, 05:18:09 pm
Quote from: "cara.mel"
You need to know how to draw glycerol.

With everything else, they can give you 2 amino acids/monosaccharides etc and get you to join them together, or vice versa. You don't have to be able to do it by heart


i remember glycerol as a carbon dining room table with 8 guests, and the hydroxys all sit on one side coz they're snobs
Title: drawing things
Post by: principe on November 13, 2007, 05:23:55 pm
Quote from: "BA22"
Quote from: "cara.mel"
You need to know how to draw glycerol.

With everything else, they can give you 2 amino acids/monosaccharides etc and get you to join them together, or vice versa. You don't have to be able to do it by heart


i remember glycerol as a carbon dining room table with 8 guests, and the hydroxys all sit on one side coz they're snobs

That's pretty clever!  :D
Title: drawing things
Post by: Collin Li on November 13, 2007, 05:34:17 pm
It doesn't really matter if you don't draw them on the same side. If it did, you'd get an isomer out of it. The C-C bond can actually freely rotate, so those -OH groups could (in reality) actually end up facing in opposite directions.

You should know alanine and glycine.
Title: drawing things
Post by: Ninox on November 13, 2007, 06:01:49 pm
Also on drawing. Complex ions
I know the arrangement, but by VCAA standards, can we put the charge on the actual ion and then when we box the whole thing, put the charge on as a superscript and still get the mark?
Title: drawing things
Post by: Collin Li on November 13, 2007, 06:32:27 pm
Quote from: "Ninox"
Also on drawing. Complex ions
I know the arrangement, but by VCAA standards, can we put the charge on the actual ion and then when we box the whole thing, put the charge on as a superscript and still get the mark?


I don't think the examiner will care a whole lot. Why? In reality there are no charges localised in the system because the ligands are actually covalent bonds. Don't listen to what I said though, if you say that, the VCAA guys will mark you wrong. You should put the overall charge outside the box.
Title: drawing things
Post by: kingmar on November 13, 2007, 06:38:31 pm
According to the VCAA Assessment Report 2006:

The sketch needed to have correct orientation of ligands. The ammonias should have been more or less symmetrically around the Ni and the N atoms of the ammonia molecules, in structural form, pointing towards the Ni*; the 2+ may have been either directly on the Ni or shown as applying to the whole complex ion or in both such places.
Title: drawing things
Post by: ninwa on November 13, 2007, 06:53:49 pm
I asked one of our chem teachers this yesterday actually. She said it doesn't REALLY matter, but to be on the safe side, put a charge on both the central metal cation AND outside the brackets. Then there's no way in hell they can mark you wrong (whereas if you put it only outside and they decided they were gonna be tight and wanted it inside as well, there goes your mark)

LOL at BA22's glycerol thing :P
Title: drawing things
Post by: kingmar on November 13, 2007, 07:29:04 pm
I don't even put brackets. VCAA don't.