Natures Chemistry - Soaps, Detergents and Emulsions

Question 1

How are soaps produced?

Answer 1

Hydrolysis of fats and oils produces three fatty acid molecules and one glycerol molecule. The fatty acids are neutralised by the alkali, forming soaps.

Question 2

What are the qualities of the soap ion head?

Answer 2

• Polar.
• Hydrophilic.
• Negative.

Question 3

What is the relation between soaps and carboxylic acids?

Answer 3

Soap is the salt of carboxylic acid.

Question 4

Which part of the soap ion buries itself in the oil/grease and why?

Answer 4

The hydrophobic tail as it doesn’t dissolve in water.

Question 5

What are the qualities of the soap ion tail?

Answer 5

• Non-polar.
• Hydrophobic.
• Positive.

Question 6

Describe the process of the oil/grease breaking up.

Answer 6

The soap ion tail buries itself in the grease, meaning, the grease has a negative charge due to the soap ion head surrounding it. Agitation causes ball-like structures to form. These repel each other due to the negative charge and the grease is now suspended in the water. This allows them to be washed away.

Question 7

What is the difference between a soap and a detergent?

Answer 7

The head of the detergent will always be soluble in water and will not form a precipitate in hard-water areas.

Question 8

What is hard water and what happens when it is mixed with soap?

Answer 8

Hard water contains dissolved metal ions causing a scum to form when mixed with soap.

Question 9

What is an emulsion?

Answer 9

A liquid that contains small droplets of another liquid.

Question 10

What is an emulsifier?

Answer 10

An emulsifier keeps water-soluble compounds and oil-soluble compounds together.

Question 11

Give two examples of emulsions and emulsifiers.

Answer 11

1. Soap acts as an emulsifier for oil and water.

2. Milk contains water and fats but uses an emulsifier to bring the two together.