Header Ads

Synthetic Materials:

Material created by man using the natural materials is known as the synthetic materials. Some important synthetic materials are given below:

Cement:

  • Discovered by English Mason, Joseph Aspdin, he named it Portland cement.
  • Limestone, clay and gypsum are some important raw material that is required in the manufacturing of the cement.
  • When cement is mixed with water and left for some time, it becomes a hard mass. This is known as setting of Cement, it is an exothermic process that’s why sprinkling of water is done for few days for a new construction.
  • Mortar is a mixture of cement, sand and water; it is used for plastering walls and binding bricks.
  • Concrete is a mixture of cement, sand, gravel and water. It is used for the construction of floors.
  • Structure having iron rods embedded in wet concrete is known as reinforced concrete.

Glass:

  • It is a super cooled liquid of silicate, it is amorphous in nature.
  • Raw material used for the formation of glass is sodium carbonate, calcium carbonate and sand.
  • Sudden cooling of molten glass make it brittle if cooled very slowly make it opaque.
  • The process of slow and uniform cooling is called annealing.
  • When glass is attacked by hydrofluoric acid, it is called etching of glass.
  • Coloured glass is obtained by adding certain metallic oxides or salts to the molten glass.


Types of glasses and their uses

Soft glass (Soda Glass):
  • Mixture of sodium or calcium silicate.
  • Used in making of glass, mirrors and common glass ware etc.
Hard Glass:
  • Mixture of potassium and calcium silicates.
  • Resistant to the action of acids and used for making hard glass.
Pyrex glass (Borosilicate glass) :
  • Used by fusing a mixture of sand, lime, borax and alkali carbonates.
  • Used in making of pharmaceuticals containers.
Glass fibre:
  • Glass wool is an excellent heat insulator.
  • Used in insulating material in oven, refrigerator.

Chemicals Used in Agriculture:

Fertilisers:
  • These are the chemical substances which are rich in a particular nutrient.
  • They supply nitrogen phosphorus and potassium.
  • Excess used of fertilisers can reduce the fertility of soil.
  • Good fertilisers are easily dissolved in water and stable so that elements are retained for longer duration.
  • It should not disturb the pH level of the soil.
  • Urea is the best fertilisers.
  • Calcium superphosphate, nitro phosphate, triple phosphate and phosphatic slag (Thomas slag) are some important phosphatic fertilisers.
  • Mixture of nitrogenous, phosphatic and potash fertilisers in proper ration is called NPK fertilisers.
  • NP fertilisers are prepared by mixing nitrogenous and phosphatic fertilisers in a definite ratio.
Pesticides:
Pesticides are the chemicals which are used to kill pests which adversely affect the crops e.g. DDT and malathion. They can be categorised into the following category:
  • Insecticides
  • Fungicides
  • Nematicides
  • Molluscicides
  • Herbicides
  • Rodenticides: Zinc phosphide is used to kill rodents.

Explosives

  • These are the substance which contains a great amount of stored energy that can produce an explosion.
  • Chemical explosives may consist of either a chemically pure compound such as nitroglycerine or a mixture of a fuel and an oxidiser.

Types of Explosives:

Primary Explosives:
  • A relatively small amount of energy is required for initiation.
  • Use in detonators e.g. acetone peroxide, silver azide and ammonium permanganate.
Secondary Explosives:
  • Are less sensitive and require more energy for initiation.
  • RDX and TNT are some secondary explosives.
Tertiary Explosives:
  • Used in large scale mining and construction operation and in terrorism.
  • Nitro-glycerine is a highly unstable and sensitive liquid also called Noble’s Oil.
  • Dynamite is a mixture of highly sensitive nitro-glycerine with saw dust, powered silica.
  • RDX (Research and development explosive) is a very powerful explosive.

Dyes:

  • Colured substances used for colouring wool, textiles materials and foodstuffs.
  • A material which is used as dyes must be able to fix itself to the material it is applied and must be resist the action of water, acids and alkalies.

Dyes can be classified into the following category:

Azo Dyes:
  • These dyes contain the azo group (-N=N-).
  • Formed during the coupling reactions, e.g. red, orange.
Indigoid Dyes:
  • These dyes contains indigoid group in their molecules e.g. indigo.
Anthraquinone dyes
Phthalein Dyes

On the basis of their applications dyes can be classified into the following types:

Vat Dyes: these dyes are water insoluble dyes and applied to fibre cotton and are obtained from indigo dyes.
Direct Dyes: these dyes can be applied to the fabric from their aqueous solution.
Acid dyes: used as their sodium salts which are soluble in water.
Basic dyes: In acidic medium these dyes are used to dye modified nylons and polysters e.g. aniline yellow and malachite green.