Biofuels

[Blondie21]

What do we need to know from this chapter? I feel as though I have read through a lot of irrelevant info as the questions in the text book do not relate to the majority of the chapter.

what do I need to know about biofuels for the exam?

Sorry if this is a broad question. If it is, I'll post my specific questions instead.

[jgoudie]

In my opinion the biofuels area is mainly just an application of the organic pathways section, in that it is mainly about the formation of an ester, through hydrolysis and esterfication/condensation reaction.  Then the combustion of that ester to generate energy (which you will learn even more about in unit4)

Yes you should be aware of the "green chemistry" aspect, but by now that should be pretty straight forward, common sense stuff.  It is advisable to know a good definition for carbon neutral and how it applies to biofuels.

The fermentation of glucose is an important reaction to know, but really that can come by thinking about reactant and products then balancing it using the C -> H -> O steps.

So yeah, get to know the organic pathways (ester / combustion) and use common sense theory to get you through the most of it. (do lots of exam questions so you know how they like to word things)

What do we need to know from this chapter? I feel as though I have read through a lot of irrelevant info as the questions in the text book do not relate to the majority of the chapter.

what do I need to know about biofuels for the exam?

Sorry if this is a broad question. If it is, I'll post my specific questions instead.

[Blondie21]

Can someone please expain MCQ9 from the 2011 chem paper to me?

[Yacoubb]

Can someone please expain MCQ9 from the 2011 chem paper to me?

Okay so in the beaker there are two layers; layer A and layer B. Layer A contains the biofuel. Ethanol is a biofuel, meaning it will be present in layer A. This eliminates III. Hence, it gives us A.

[Blondie21]

Okay so in the beaker there are two layers; layer A and layer B. Layer A contains the biofuel. Ethanol is a biofuel, meaning it will be present in layer A. This eliminates III. Hence, it gives us A.

yeah but how do you know that it is layer A

[Blondie21]

omg... I didn't read the question properly..

Sorry! -.-

[Yacoubb]

yeah but how do you know that it is layer A

We're told that the biofuel exists in layer A. Ethanol is a biofuel and so it will be present in layer A. The question asks what willbe present in layer B. This means option I and option II are in layer B, and not option III (which is ethanol). Thus, the answer is A.

It's probably a good idea to memorise biofuels.

[Blondie21]

We're told that the biofuel exists in layer A. Ethanol is a biofuel and so it will be present in layer A. The question asks what willbe present in layer B. This means option I and option II are in layer B, and not option III (which is ethanol). Thus, the answer is A.

It's probably a good idea to memorise biofuels.

Yeah

On the study guide it says 'condensation reactions that produce lipids (limited to triglycerides)"

Does that mean to need to memorise that entire reaction as well?

[Yacoubb]

Yeah

On the study guide it says 'condensation reactions that produce lipids (limited to triglycerides)"

Does that mean to need to memorise that entire reaction as well?

As you know, a triglyceride is made up of a glycerol molecule with three fatty acid hydrocarbon chains attached. You need to know that the attachment of the fatty acid molecules to the glycerol molecule occurs by a condensation reaction, where a water molecule is eliminated to allow for the formation of a covalent bond between the fatty acid & the glycerol. If I'm not mistaken, the bond is an ester linkage.

[Blondie21]

As you know, a triglyceride is made up of a glycerol molecule with three fatty acid hydrocarbon chains attached. You need to know that the attachment of the fatty acid molecules to the glycerol molecule occurs by a condensation reaction, where a water molecule is eliminated to allow for the formation of a covalent bond between the fatty acid & the glycerol. If I'm not mistaken, the bond is an ester linkage.

Yes that's correct

Do we need to memorise the structure of glycerol, fatty acids and a triglyceride molecule?

[Yacoubb]

Yes that's correct

Do we need to memorise the structure of glycerol, fatty acids and a triglyceride molecule?

The structure of glycerol is found in the data book. You definitely don't need to memorise fatty acids, and I'd probably note the arrangement of the triglyceride molecule (I'd probably note the ester linkage, and the product of the condensation reaction).