KERALA PSC / CHEMISTRY / CHEMISTRY IN DAILY LIFE / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY

 

KERALA PSC / CHEMISTRY / CHEMISTRY IN DAILY LIFE / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY

KERALA PSC / CHEMISTRY / CHEMISTRY IN DAILY LIFE / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY

 

Polymers

·      Complex molecules formed by the addition of simple molecules are called polymers

·      Cellulose and silk are natural polymers and nylon, rayon, Teflon etc… are man-made polymers

·      Thermoplastics and thermosetting plastics are two types of plastics

·      Polythene, nylon etc…, are example for thermoplastics and polyester, bakelite etc., are examples for thermosetting plastics

·      Rayon is known as artificial silk and is used in carpets, tyrecode, surgical dressings, fabrics etc…

·      Caprolactum [(C₆H₁₁NO] is produced from cyclohexane

·      Nylon 66 (Polyamide), Orlon, Terylenear, Polyester, Rayon are synthetic fibres

·      PVC is used for the manufacture of Electrical insulators water proof cloth etc…

·      Bakelite is made from phenol and formaldehyde

·      Polyvinyl chloride (PVC) and Polyvinylacetate (PVA) are polymers of vinylchloride and vinylacetate

·      Nylon – 66, Nylon – 6 are synthetic fibres belonging to polyamide

·      Rayon is called artificial silk

 

Rubber

·      Rubber is a polymer of isoprene

·      Rubber is a naturally available elastic polymer

·      Ordinary rubber is a thermoplastic substance

·      If Sulphur is added to rubber and heated, its shape can be maintained and its hardness increased. The process of heating rubber with Sulphur for the betterment of its properties, is called vulcanization

·      Vulcanization enhances the following properties of rubber: tensile strength, hardness, elasticity, ability to withstand heat changes

·      These properties can be varied by changing the quantity of Sulphur, temperature and time taken for vulcanization

·      Tyres filled with air are called pneumatic

·      Many man made substances are not bio-degradable

·      Vulcanization is carried out by heating the crude rubber in presence of Sulphur

·      Buna rubber, SBR, neoprene, Butyl rubber, Thiokoil & Buna N are examples of synthetic rubber.

Cement

·      Cement is complex mixture of aluminates and silicates

·      In 1824, a British Engineer, Joseph Aspidin made a binding material by mixing lime and silica and firstly it was named as ‘portland cement’.

·      The setting of cement is due to the hydration of calcium silicates and calcium aluminates

·      The mixture of cement, silica and water is called cement mortar

·      Concrete is reinforced by embedding steel in cement

·      A suitable site of a cement plant requires proximity to limestone and gypsum

·      Gympsum is CaSO₄.2H₂O

 

Manufacture of cement

The raw material is ground into a fine powder and mixed in the fixed proportion. This is heated in a furnace at a high temperature (1500ºC). Clinkers, which is a complex mixture of calcium silicate and calcium aluminate is formed. Gypsum is added to clinker and the mixture is powered to make cement.

 

KERALA PSC / CHEMISTRY / CHEMISTRY IN DAILY LIFE / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY