Esters, Fat and Oils

Question 1

State the ester link

Answer 1

COO

Question 2

Name and draw esters

Answer 2

Esters are produced from a reaction between an alcohol and a carboxylic acid.

The name of an ester comes from its ‘parent’ alcohol and carboxylic acid.

Methyl ethanoate

Propyl methanoate

Question 3

State the uses of esters

Answer 3

Esters are used as flavourings, fragrances (often have pleasant, fruity smell) and solvents for other non-polar compounds.

Question 4

State the reaction that forms and breaks esters apart

Answer 4

Condensation forms esters.

Hydrolysis breaks esters.

Question 5

Describe a condensation reaction

Answer 5

Esters are formed by a condensation reaction between an alcohol and a carboxylic acid with the elimination of water.

Question 6

Describe a hydrolysis reaction

Answer 6

Hydrolysis is breaking a large molecule to smaller ones by the addition of water. The ‘parent’ alcohol and carboxylic acid are formed

Question 7

Describe how edible fats and oils are formed

Answer 7

Edible fats and oils are esters formed from the condensations of glycerol (propan-1,2,3-triol).

You must be able recognise and name this molecule as well as 3 carboxylic acids (fatty acids).

Question 8

Explain why there is a difference in melting points of fats and oils

Answer 8

Oils have a lower melting point than fats.

Oils have more unsaturated (more double bonds). These double bonds prevent the molecules from packing as closely together, so the intermolecular forces are weaker - leading to a lower melting point.

Question 9

Describe the test for saturation

Answer 9

Unsaturated compounds will decolourise bromine water quicker/require less bromine solution

Question 10

Describe why we need fats and oils

Answer 10

Fats and oils are a really concentrated source of energy for us. They are also essential for the transport and storage of fat-soluble vitamins for our bodies.