Corossion of metals

Corrosion is defined as an attack on a material as a result of chemical, frequently electrochemical reaction, with the surrounding medium. According to this definition, the term corrosion can be applied to all materials, including non-metals. But in practice, the word corrosion is mainly used in conjunction with metallic materials. Why do metals corrode? Apart … Read more

Acids and bases

Acid An acid is a substance which forms H+ ions as the only positive ion in aqueous solution. Examples:- Hydrochloric acid dissolved in water forms H+ and Cl– ions   HCl —> H+ + Cl–   Sulphuric acid dissolved in water forms H+ and SO42- ions   H2SO4 —>2H+ + SO42-   Nitric acid forms H+ and NO3– ions when dissolved in water   HNO3 —> … Read more

The Rate of a Chemical Reaction-CGPSC Mains

The Rate of a Chemical Reaction The rate of a chemical reaction can be defined as the amount of the reaction which occurs in unit time. The rate of a reaction is measured by choosing certain properties of the reaction which will indicate how far the reaction has gone, and whose magnitude can be observed … Read more

Fast and slow chemical reactions

Slow reactions Chemical reactions that occur very slowly and can take a long time for completion are called slow reactions. Usually covalent compounds are involved in slow reactions. Some reactions can take days, weeks and months to complete; they are called very slow reactions. For example, Milk may take several hours or a day to convert to curd, while … Read more

Metallurgy concentration, roasting, smelting

Metallurgy concentration, roasting, smelting Roasting It is a process wherein the ore is heated either alone or with some other material in excess of air below the fusion point of the ore. Usually, this method is used for sulphide ores. In roasting, definite chemical changes take place to form oxide or chloride of the metal. … Read more

Properties of polyvinyl chloride

Properties of polyvinyl chloride What is Polyvinyl Chloride (PVC), and What is it Used For? Polyvinyl Chloride (PVC) is one of the most commonly used thermoplastic polymers in the world (next to only a few more widely used plastics like PET and PP). It is a naturally white and very brittle (prior to the additions of plasticizers) plastic. PVC has been around longer … Read more

Metallurgy of iron

Metallurgy of iron Iron is an important constituent of hemoglobin, which is in blood. Iron is the metal used most widely in industries and hence may be called the king of metals. It is the second most abundant metal after aluminum. Iron does not occur in native state, since it is oxidized easily. Ores of Iron Chemical Name Chemical … Read more

Properties of teflon

Properties of teflon Polytetrafluoroethylene or PTFE (more commonly known as Teflon) is a particularly versatile ivory-white and opaque plastic fluoropolymer; it is made by the free-radical polymerisation of many tetrafluoroethene molecules, and is suitable for a wide range of applications in industries as diverse as aerospace, the food and drink industry, pharmaceuticals and telecoms. Produced by … Read more

Exothermic and endothermic reactions

Endothermic Reactions Endothermic reactions are those chemical reactions where energy is absorbed by the system from the surroundings mostly in the form of heat. The concept is applied in the physical sciences like chemical reactions where hear is converted to chemical bond energy by way of experiments. Common examples of endothermic reactions are cooking an … Read more

Properties of polythene

Properties of polythene Polyethylene is a thermoplastic polymer with variable crystalline structure and an extremely large range of applications depending on the particular type. It is one of the most widely produced plastics in the world (tens of millions of tons are produced worldwide each year). The commercial process (the Ziegler-Natta catalysts) that made PE … Read more