Soaps

Question 1

How are soaps formed?

Answer 1

Soaps are formed via the alkaline hydrolysis of fats and oils.

Question 2

What is the hydrophobic part of the soap?

Answer 2

This part is the long non-polar covalent hydrocarbon tail in the soap. It is water-hating and is soluble in non-polar compounds such as grease (like dissolves like)

Question 3

What is the hydrophilic part of the soap?

Answer 3

This part is the ionic head of the soap. It is water-loving and can dissolve in ionic and polar compounds such as water.

Question 4

How does the cleansing action of soap work?

Answer 4

Step 1) The soap is added to the water and the hydrophobic and hydrophilic parts of the soap arrange themselves in grease and water respectively.

Step 2) Agitation begins to separate the grease of the surface. This process forms micelles (balls of grease droplets in water).

Step 3) The micelles are the washed away as they are suspended in water by the repulsion of the negatively charged ionic heads.

Question 5

What is an emulsion?

Answer 5

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

Question 6

What is an emulsifier?

Answer 6

An emulsifier is used to prevent non-polar and polar liquids from separating into layers.

Question 7

What is “hard water”?

Answer 7

Hard water is water than contains high levels of dissolved metal ions

Question 8

What happens when soap is used in hard water?

Answer 8

An insoluble precipitate called scum, is formed