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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: hyperblade01 on June 09, 2009, 07:14:33 pm

Title: Exam Predictions/Questions
Post by: hyperblade01 on June 09, 2009, 07:14:33 pm
I tend to look at past exams and take a guess on what's going to be on this one...

Earlier this year my teacher told me biofuels was done poorly so possibily examiners will put a question in there.


So there's ethanol, biodiesel and biogas.

Thinking it'll be biodiesel and maybe the process on how its made:

Tryglyceride + Methanol + KOH - Tryglyceride hydrolysed to give
Fatty Acid + Glycerol which react with Methanol to give
Ester + Water

Think it could get harder than that?
Title: Re: Exam Predictions/Questions
Post by: d0minicz on June 09, 2009, 07:16:22 pm
can that be shown in 1 step?
Title: Re: Exam Predictions/Questions
Post by: arthurk on June 09, 2009, 07:17:42 pm
maybe a question on why biofuel is preferred blah blah
Title: Re: Exam Predictions/Questions
Post by: hyperblade01 on June 09, 2009, 07:28:05 pm
Quote from: d0minicz on June 09, 2009, 07:16:22 pm
can that be shown in 1 step?


I don't think so because between the 3 steps not everything is used..


Title: Re: Exam Predictions/Questions
Post by: Dark Horse on June 09, 2009, 08:07:44 pm
It can be, as it is a transesterification reaction. You write the triglyceride + methanol in the presence of NaOH or KOH to produce a methyl ester (biodiesel) and glycerol
Title: Re: Exam Predictions/Questions
Post by: hyperblade01 on June 09, 2009, 08:13:06 pm
Heh, we'll just have to see


Looks like last year didnt have a DNA short answer as well - maybe draw the structure of a nucleotide (like bio :P) and a crime scene scenario :O

DNA sample > PCR > Restriction Enyzme > Electrophoresis > Match to other samples or not and why

Hope I got the process in the right order
Title: Re: Exam Predictions/Questions
Post by: Dark Horse on June 09, 2009, 08:15:34 pm
Yep, after electrophoresis, the bands are subjected to radioactive probes. Why?
Title: Re: Exam Predictions/Questions
Post by: hyperblade01 on June 09, 2009, 08:18:13 pm
Radiation used to make them visible? Or was that with dye and UV light to fluoresce it...

Or both... >.>
Title: Re: Exam Predictions/Questions
Post by: IntoTheNewWorld on June 09, 2009, 08:22:25 pm
Quote from: hyperblade01 on June 09, 2009, 08:18:13 pm
Radiation used to make them visible? Or was that with dye and UV light to fluoresce it...

Or both... >.>

I think both do the same thing, you do one or the other.

I think
Title: Re: Exam Predictions/Questions
Post by: mystikal on June 09, 2009, 08:22:51 pm
do you have to put 3 methanol and 3 fatty acids in the equations for transesterification?

or  just CH3OH + COOH-R ->CH3COO-R +h20
Title: Re: Exam Predictions/Questions
Post by: d0minicz on June 09, 2009, 08:43:49 pm
sooo they stain the electrophoresis with a radioactive dye and apply UV right ???
Title: Re: Exam Predictions/Questions
Post by: arthurk on June 09, 2009, 08:51:27 pm
draw structure of nucleotide i think going to be on it