Fats,oils, Soaps

Question 1

Explain the Properties of oils

Answer 1

• They are more unsaturated
• Less packed together
• Weaker LDFs
• Liquid at room temperature
• lower melting point

Question 2

Explain the Properties of fats

Answer 2

• more saturated
• stronger LDFs
• molecules pack tightly together
• higher melting point
• solid at room temperature

Question 3

What are fats ?

Answer 3

A source of fat-soluble vitamins around the body

Question 4

How can you make oils less unsaturated ( the gardening of oils)?

Answer 4

Oils can undergo hydrogenation making them less unsaturated

Question 5

Are fats and oils hydrophilic or hydrophobic , and are they polar or non-polar?

Answer 5

Hydrophobic (water hating)

Non polar

Question 6

Fats and oils are esters of ?

What is the ratio ?

Answer 6

Glycerol and fatty acids

1:3( 1 glycerol to 3 fatty acids)

Question 7

Name the systematic name for glycerol

Answer 7

Propan-1,2,3-triol

Question 8

What do emulsions do ?

Provide an example

Answer 8

They help water and oil milk

Example: milk

Question 9

Name the process used to make soaps. And explain what happens in it?

Answer 9

Ester hydrolysis (process) (saponification)

Forming soaps = hydrolysis of fats/oils using bases

Question 10

(Fat + oil + NaOH -> ? )

Answer 10

( fat + oil + NaOH -> glycerol + salt (sodium) )

Question 11

Draw an ester link

Answer 11

Have to .

Question 12

Fatty acids have how many ester links ?

Answer 12

3

Alkaline hydrolysis of these ester links forms glycerol and a salt (soap). The salt is soluble in water.

Question 13

Name the process used to make soaps

Answer 13

Saponification

Question 14

Explain saponification- making soaps!

Detailed answer please .

Answer 14

Hydrolysis of an ester is the opposite reaction to the formation of the ester. Therefore the products will be an alcohol (glycerol) and a carboxylic acid. The alkali used to catalyse the reaction is sodium hydroxide. This neutralises the acids formed. The fatty acids react with the NaOH and form salts. These salts are called soaps

Question 15

The head and the tail in soaps. Which is covalent and which is ionic

Answer 15

Tail is covalent (hydrophobic, so it’s soluble in oil)

Head is ionic( hydrophilic and water soluble )

Question 16

How does the head and tail work.

Detailed answers (3 marks)

Answer 16

• the hydrophobic “tail” is attached to grease/oil and the hydrophilic head is attracted to the polar water molecules
• this creates a ball-like structure
• the ball structures repel each other and this keeps the oil suspended in water

Question 17

What is meant by an emulsion?

Answer 17

An emulsion is a mixture of two or more liquids that are normally immiscible