Chapter 5 chemical 4 consumers

Chemical is very important to human beings’ life

Almost everything that we use, we eat, we drink everyday

are related closely to chemistry

For examples:-The soap we use to bath

-The detergent we use to clean

the dirt

-The food additives to make

food tasted better

-The medicines tocure disease

Who discovers the soap? And when its history

started?

Since water is essential for life, the earliest people lived near water and knew something about its cleansing

properties - at least that it rinsed mud off their hands.

A soap-like material found in clay cylinders during the excavation of ancient Babylon is evidence that

soapmaking was known as early as 2800 B.C.

At about the same time, Moses gave the Israelites detailed laws governing personal cleanliness. He also related cleanliness to

health and religious purification.

The early Greeks bathed for aesthetic reasons and apparently did not use soap. Instead, they cleaned their bodies with blocks of clay, sand, pumice and ashes, then anointed themselves with oil, and scraped off the oil and dirt with a metal instrument. Clothes were washed without soap in streams.

Soap making was an established craft in Europe by the seventh

century. Vegetable and animal oils were used with ashes of plants,

along with fragrance.

Commercial soapmaking in the American colonies began

in 1608 AD

Large-scale commercial soapmaking occurred in 1791 when a French

chemist, Nicholas Leblanc, patented a process for making soda ash, or sodium carbonate. Soda ash is the

alkali obtained from ashes that combines with fat to form soap.

20 years later, Michel Eugene Chevreul, another French

chemist, discovered that the chemical nature and

relationship of fats, glycerine and fatty acids.

Also important to the advancement of soap technology was the mid-1800s

invention by the Belgian chemist, Ernest Solvay, of the ammonia process, which also used common table salt, or sodium

chloride, to make soda ash. Solvay's process further reduced the cost of

obtaining this alkali, and increased both the quality and quantity of the soda ash

available for manufacturing soap.

What forms SOAP?• sodium (Na) @ potassium (K) salts of

long- chain fatty acid

Fats/Oil

•the ionic head group is water-

soluble, the nonpolar tail insoluble

The structure of soap

Tail TailHead

hydrophobic hydrophilic

The structure of soap

The structure of soap

Tail

How SOAP & water can clean so much than water ?

Cleansing Action

•Hidrophilic part (head) attracted to water

Water molecules

Cleansing ActionDirt

(grease)

Hidrophobic part (tail)

likes to dissolved in

grease

Cleansing Action

•The droplets do not coagulate because of repulsion between negative charges on surface

•Scrubbing clothes helps to break the grease into small droplets

Cleansing Action•The droplets suspended in water & form emulsion

•Rinsing process could wash away these droplets & leaves surface clean

Cleansing Action

Cleansing Action

Detergent

•Soaps are made up of natural resources

•But detergents are made up of synthetic resources such as petroleum fractions

Structure of Detergent

Tail Head

Cleansing Action

•Cleansing action of detergent is just the same with soaps

Soap Detergent

Advantage• Biodegradable•Do not cause any pollution

• effective in both of soft & hard water•do not form scum in hard water (Mg2+ ,Ca 2+)•Do not form precipitate in acidic water

Disadvantage• form scum in hard water, cleansing action not effective•Form precipitate in acidic water

• Non-biodegradable• harm aquatic lives