How to prepare soaps

Preparation of soap

Soaps are the metal (commonly sodium or potassium) salts of long chain fatty acids mainly palmitic (C15H31COOH), stearic (C17H35COOH) and oleic (C17H33COOH) acids.

Raw Materials

Tallow is the principal fatty material in soap making. Other than tallow any vegetable oil, e.g; cotton seed oil, linseed oil or palm oil may also be used. Caustic soda (NaOH) or Caustic potash (KOH). Most of the soaps now-a-days are made commercially in large units called “kettles” similar to the one shown in figure . Animal fat or tallow is placed at the bottom of the large tank and alkali (NaOH) is added. The reaction which follows is called sapon keeps on floating at the top. Glycerine and salt solution is drained off from the bottom of the tank from which glycerine is recovered as a by-product.

Laundry Soap

The solid soap is mixed with a resin and more caustic soda solution is added and heated again. The molten mixture on cooling is moulded into cakes. Sodium silicate, washing soda and sodium phosphate are also added to this soap to increase its weight and to improve its quality.

Toilet Soap

Toilet soap is prepared from a good quality fat or edible oil. The moisture is removed from soap by passing it through hot rollers and then desired colour and perfume are added.

Kitchen Soap

The Kitchen soap contains finely divided sand and washing soda. It is used forwashing utensils.

Shaving Cream

Shaving cream or soap is produced by the saponification of good quality animal fat or edible oil with potassium hydroxide (caustic potash). It also contains some extra quantity of stearic acid to prevent soap from drying.
Detergents
Detergents are the salts of organic sulphonic acids. The general formula of a detergent is R-C6H4-S03Na+ (sodium alkyl benzene sulphonate). All these detergents contains a polar group, Examples Sodium lauryl sulphate Sodium dodecylbenzene sulphonate Detergents when dissolved in water reduce the intermolecular attractive forces between water molecules.
Therefore, water containing some detergent enters into the clothes with greater ease and cleans them by removing dust and grease etc. from the surface.

Plastic

Plastics are synthetic resins which are rapidly becoming important in everyday life. These are classified into two types:
Thermoplastics
Thermosetting plastics

Thermoplastics

These are the plastics which can easily be softened when heated and become hard when cooled with a little change in their properties. When heated they melt and form a fluid which can be moulded into any desired shape and then cooled to get the desired product. Common examples are polythene, polypropylene, polyvinyl chloride etc.

Thermosetting Plastics

These are the plastics which undergo permanent change on heating. When heated they get highly cross linked to form hard, infusible products. Common examples are bakelite, melamine etc.

Methods of preparation and uses of plastics

Polythene

It is prepared by the polymerization of ethjfrie under high pressure and in the presence of traces of oxygen (0.01 %)

nCH2 = CH2 ► —{-H2C— CH2)t-

It is used in the manufacture of pipes, laboratory apparatus, bottles, buckets, toys and electrical insulators.

Polyvinyl chloride (PVC)

It is prepared by the polymerization of vinyl chloride (CH2=CHCI) in an autoclave PVC is used: in the manufacture of rain coats and hand bags. for artificial flooring. as a good insulating material for wires and other electrical goods.

Polystyrene

It is prepared by the polymerization of styrene in the presence of benzoyl neroxide. It is resistant to shock and chemical action. It is used for: making hot drink cups, toys, combs, etc. making radio and television bodies. Making tiles to be used in covering ceilings and floors. Teflon (Polytetrafluoroethylene) It is prepared by the polyemerization oftetrafluoroethylene. Pressure It is used in the manufacture of non-stick utensils.