2e) - Soaps Detergents And Emulsions

Question 1

What process are soaps produced by

Answer 1

Soaps are produced by the alkaline hydrolysis of edible fats and edible oils

Question 2

What does hydrolysis of a typical fat or oil produce

Answer 2

Hydrolysis produces three fatty acid molecules and one glycerol molecule

Question 3

What are the fatty acids neutralised by when a soap is made

Answer 3

The fatty acid molecule are neutralised by the alkali forming water soluble, ionic salts called soaps

Question 4

What are ionic salts also called

Answer 4

Soaps

Question 5

Produce a diagram of alkaline hydrolysis of edible fats and edible oils

Answer 5

Check jotter for answer

Question 6

What substances can soaps remove

Answer 6

Soaps can be used to remove non - polar substances such as oil and grease

Question 7

What type of tails do soaps have

Answer 7

Soap ions have long non-polar tails, readily soluble in non-polar compounds (hydrophobic)

Question 8

What is the covalent hydrocarbon tail known as

Answer 8

Hydrophobic

Question 9

What is the hydrophobic tail soluble in

Answer 9

The hydrophobic tail is non polar so soluble in non-polar substances such as oil (like dissolves like)

Question 10

What is the name of the ionic head

Answer 10

Hydrophilic

Question 11

What type of head do soap molecules have

Answer 11

Ionic heads that are water soluble - hydrophilic

Question 12

What happens to the hydrophobic tail when removing a stain

Answer 12

The hydrophobic tails dissolve in the oil or grease

Question 13

What happens to the hydrophilic head when removing a stain

Answer 13

The negatively charged hydrophilic heads remain in the surrounding water

Question 14

How does agitation remove the stain

Answer 14

agitation causes ball like structures to form. The negatively charged ball like structures repel each other and the oil or grease is kept suspended in the water

Question 15

What is the summary of how a stain is removed

Answer 15

The hydrophobic tails dissolves in the oil or grease. The negatively charged hydrophilic head remain in the surrounding water. Agitation causes ball like structures to form. The negatively charged ball like structures repel each other and the oil or grease is kept suspended in the water

Question 16

Describe where the two parts of the soap molecule dissolve

Answer 16

Hydrophilic Ionic head sticks out of grease and is soluble in water

Hydrophobic tail dissolves in oil or grease as it is soluble in non polar substances

Question 17

Draw a diagram showing what happens during the removal of a stain

Answer 17

Check jotter for answer

Question 18

What is hard water

Answer 18

Hard water is a term used to describe water containing high levels of dissolved metal ions

Question 19

What happens when soap is used in hard water

Answer 19

When soap is used in hard water, scum an insoluble precipitate is formed

Question 20

What are soapless detergents

Answer 20

Soapless detergents are substances with non - polar hydrophobic tails and ionic hydrophilic heads. These remove oil and grease in the same way as soap

Question 21

Why use soapless detergents

Answer 21

Soapless detergents do not form scum with hard water

Question 22

What is an emulsifier used for

Answer 22

An emulsifier can be used to prevent non-polar and polar liquids separating into layers

Question 23

What does an emulsion contain

Answer 23

An emulsion contains small droplets of one liquid dispersed into another liquid

Question 24

How can emulsifiers for use in food be made

Answer 24

Emulsifiers for use in food can be made by reacting edible oils with glycerol

Question 25

What are the hydroxyl groups in emulsifiers

Answer 25

The hydroxyl groups present in the emulsifier are hydrophilic

Question 26

What are the fatty acids in emulsifiers

Answer 26

the fatty acid chains are hydrophobic.

Question 27

How is a stable emulsion formed

Answer 27

The hydrophobic fatty acid chains dissolve in oil whilst the hydrophilic hydroxyl groups dissolve in water, forming a stable emulsion