Everything Science Grade 12

CHAPTER 5. THE CHEMICAL INDUSTRY 5.3

H

H C O C

O

(CH 2 ) 14 CH 3

H C O C

O

(CH 2 ) 14 CH 3

H C O C

O

(CH 2 ) 14 CH 3

H

glycerol fatty acids

Figure 5.7: The structureof a fat, composed of analcohol and three fatty acids

hydrophilic, meaning that it is attracted to water. Let’s imagine that we have

added soap to water inorder to clean a dirty rugby jersey. The hydrocarbon

chain will attach itself tothe soil particles in the jersey, while the carboxylic acid

will be attracted to the water. In this way, the soil is pulled free of the jersey and

is suspended in the water. In a washing machineor with vigorous handwashing,

this suspension can be rinsed off with clean water.

DEFINITION: Soap

Soap is a surfactant thatis used with water for washing and cleaning.

Soap is made by reacting a fat with either sodium hydroxide (NaOH)

or potassium hydroxide(KOH).

2. Detergents

DEFINITION: Detergent

Detergents are compounds or mixtures of compounds that are used to

assist cleaning. The termis often used to distinguish between soap and

other chemical surfactants for cleaning.

Detergents are also cleaning products, but are composed of one or more surfac-

tants. Depending on thetype of cleaning that is needed, detergents may contain

one or more of the following:

• Abrasives to scour a surface.


• Oxidants for bleaching and disinfection.