Lisachem 2009 question help

[mystikal]

i have no idea how to do parts of quesiton 4 (a,b,c) == can somebody help? Lisachem 2009 Chemistry
what the heck is transesterification do we need to know that?
and whats iodine numbers

[chem-nerd]

yes, all of this content is assessable.

Iodine number refers to how much iodine is required to 'add' to all of the double bonds in a fatty acid. So work out n(fatty acid), multiply by however many double bonds are in each fatty acid and this will give you the n(I₂) required. (each I₂ molecule undergoes an addition reaction with a single double bond. be wary of whether they give you infomation on a fatty acid or a triglyceride when calculating n)

Transesterification is just the process of swapping the alkanol of an ester with another alkanol. In the case of biodiesel, that means replacing glycerol with methanol (usually). Triglyceride is broken down via a hydrolysis reaction in the presence of a catalyst and then the 3 fatty acids are reacted with methanol to make biodisel.

[mystikal]

seriously! zomgs ive never seen any of these things in the chem textbooks

[vamsiaus]

neither have I, first time hearing about it. Can somebody confirm if this is in the course.

[ice_blockie]

Iodine number is not mentioned explicitly in the study design to my knowledge however, having looked at the question, you SHOULD be able to complete the question without previous knowledge - it is part of the chemistry design's key skills where you should be able to

"make connections between concepts; process information; apply understandings to familiar and new contexts"

i.e. the new context being iodine numbers - rest assured though that anything you haven't covered will be explained to you.

Transesterification, however needs to be understood. It combines two key points for Unit 3 Area of Study 2 - that of biofuels (biodiesel in particular) and organic reaction pathways.

Though you shouldn't fret, these two things don't make for much of the course.