U2-2-2 - Fats and Oils

Question 1

Name this molecule

Answer 1

Propane-1,2,3-triol
OR
glycerol

Question 2

Fats and oils belong to this family of compounds

Answer 2

Esters

or triesters (3 ester links per molecule)

Question 3

Fats and oils are made from these two components

Answer 3

Glycerol and fatty acids

Question 4

When a fat/oil gets hydrolysed, what is the molar ratio of glycerol to fatty acids?

Answer 4

1:3

1 mole glycerol to 3 moles fatty acids

Question 5

How can you tell from its formula if a fatty acid is saturated?

Answer 5

If it’s saturated, the general formula is C_nH_2n+1COOH.

Every 2 missing hydrogens = one double bond (C=C)

Question 6

What is the structural difference between fats and oils?

Answer 6

Fats are saturated, oils are unsaturated

Question 7

What practical technique and reagent can be used to work out the degree of unsaturation in an oil?

Answer 7

Titration with bromine water

Moles of Br₂ reacted = moles of C=C present

Question 8

Name the process through which oils are turned into fats

Answer 8

(Partial) hydrogenation

Question 9

Which have the higher melting points: fats or oils?

Answer 9

Fats

Question 10

Why are the melting points of fats higher than those of oils?

2 reasons

Answer 10

Fat molecules** pack more closely** together.

London dispersion forces are stronger between fat molecules .