Exam Suggested Solutions

[csq7]

7C part 2 short answer i kinda disagree because... it is due to the fact that ethanol comes from glucose (plant material) hence it is a biochemical fuel. And not that it is produced by fermentation from yeast.

[Mao]

7C part 2 short answer i kinda disagree because... it is due to the fact that ethanol comes from glucose (plant material) hence it is a biochemical fuel. And not that it is produced by fermentation from yeast.

ethanol also comes from ethene industrially. that was the differentiating point: how and where it come from.

[Collin Li]

http://butane.chem.uiuc.edu/cyerkes/Chem104A_BFA05/Genchemref/nomenclature_rules.html

"The halogen is treated as a substituent on an alkane chain. The halo- substituent is considered of equal rank with an alkyl substituent in the numbering of the parent chain."

[equinox]

lol this is crazy....I wonder how vcaa are gonna sort their way through these naming issues and how strict they are gonna b about the IUPAC conventions.

[Charbel]

Question 1 in your short answer is incorrect.. have another look at the graph.. it isnt at 90ml it's actually at 80-85ml =[ i got 0.2 =D

[csq7]

your answer states "it is a biological process in yeast" but not exactly where that ethanol came from. so i dont think its sufficient to get the mark

[Mao]

Question 1 in your short answer is incorrect.. have another look at the graph.. it isnt at 90ml it's actually at 80-85ml =[ i got 0.2 =D

yyeaaah? why does that matter though?

its gravimetric analysis.... why does the volume of the precipitating agent need to be known at all? its always in excess!

[Rayle]

Okay, I'll concede. I was wrong .

[Mao]

your answer states "it is a biological process in yeast" but not exactly where that ethanol came from. so i dont think its sufficient to get the mark

it is consequential from the previous question [fermentation of glucose], which i did mention in the actual answer I wrote.

and:
    ii. Explain why ethanol produced by fermentation is refferred to as a "biochemical fuel" (1 mark)
    it is a biological process in yeast

the actual questioning does state the source already [fermentation], so just gotta explain why its biological!

[however, the solutions have been modified now]

[Charbel]

Question 1 in your short answer is incorrect.. have another look at the graph.. it isnt at 90ml it's actually at 80-85ml =[ i got 0.2 =D

yyeaaah? why does that matter though?

because in fact.. 80ml x 0.01M was needed not 90ml x 0.02M.. you now have .. excess mole.

have a look on the graph you take the to the point of the linear region cutting off.

well at least i think so.

[Mao]

Question 1 in your short answer is incorrect.. have another look at the graph.. it isnt at 90ml it's actually at 80-85ml =[ i got 0.2 =D

yyeaaah? why does that matter though?

because in fact.. 80ml x 0.01M was needed not 90ml x 0.02M.. you now have .. excess mole.

have a look on the graph you take the to the point of the linear region cutting off.

well at least i think so.

what are you talking about =\



volume doesnt come into it at all~

and where did 0.01 M come in?

[csq7]

i think you misinterpreted the qn. fermentation is not the source of ethanol. the ethanol came from plants and it is the main reason why it is a biochemical fuel. fermentation is how the glucose became ethanol which they are testing in part 1. and theres nothing in the qn that asks why is it biological. they are just asking why is it a biochemical fuel.

[Mao]

i think you misinterpreted the qn. fermentation is not the source of ethanol. the ethanol came from plants and it is the main reason why it is a biochemical fuel. fermentation is how the glucose became ethanol which they are testing in part 1. and theres nothing in the qn that asks why is it biological. they are just asking why is it a biochemical fuel.

oh right, do you mean yeast need to be mentioned? [i did that too in the exam, but havent put that in]

biochemical fuels simply refer to fuels that come from a biochemical pathway... the biological process of fermentation is a biochemical pathway, so i dont see how making this particular distinction serves this purpose?

[csq7]

i see your point now and i slightly disagree with it. "biochemical fuels simply refer to fuels that come from a biochemical pathway" that isnt quite right. read the tb page `168 it clearly says bio chemical fuels are fuels derived from plant materials such as grains.. et cetc  so i guess thats where you went wrong

[Mao]

i see your point now and i slightly disagree with it. "biochemical fuels simply refer to fuels that come from a biochemical pathway" that isnt quite right. read the tb page `168 it clearly says bio chemical fuels are fuels derived from plant materials such as grains.. et cetc  so i guess thats where you went wrong

but i did say that in my exam answer!

[just that i thought that was the not-important part, and wrote up what I thought is important instead]

mind writing up the solution to this question and I'll add it to the first post?