Give the uses of freon 12, DDT, carbon tetrachloride and iodoform.
Uses of Freon − 12
Freon-12 (dichlorodifluoromethane, CF2Cl2) is commonly known as CFC. It is used as a refrigerant in refrigerators and air conditioners. It is also used in aerosol spray propellants such as body sprays, hair sprays, etc. However, it damages the ozone layer. Hence, its manufacture was banned in the United States and many other countries in 1994.
Uses of DDT
DDT (p, p−dichlorodiphenyltrichloroethane) is one of the best known insecticides. It is very effective against mosquitoes and lice. But due its harmful effects, it was banned in the United States in 1973.
Uses of carbontetrachloride (CCl4)
(i) It is used for manufacturing refrigerants and propellants for aerosol cans.
(ii) It is used as feedstock in the synthesis of chlorofluorocarbons and other chemicals.
(iii) It is used as a solvent in the manufacture of pharmaceutical products.
(iv) Until the mid 1960’s, carbon tetrachloride was widely used as a cleaning fluid, a degreasing agent in industries, a spot reamer in homes, and a fire extinguisher.
Uses of iodoform (CHI3)
Iodoform was used earlier as an antiseptic, but now it has been replaced by other formulations-containing iodine-due to its objectionable smell. The antiseptic property of iodoform is only due to the liberation of free iodine when it comes in contact with the skin.
Iodoform: It was earlier used as an antiseptic but the antiseptic properties are due to the liberation of free iodine and not due to iodoform itsdf. Due to its objectionable smell, it has been replaced by other formulations containing iodine.
(i)As an industrial solvent for oil, fats, resins etc.and also in dry cleaning.
(ii)CCl4 vapours are highly non inflammable, thus CCl4 is used as a fire extinguisher under the name pyrene.
(iii)Used in the manufacture of refrigerants and propellants for aerosol cans.
Freons: Freon-12 (CCl2F2) is most common freons in industrial use.
Uses: For aerosol propellants, refrigeration and air conditioning purposes.
DDT (p -p’ – Dichloro diphenyl – trichloro ethane):
(i)The use of DDT increased enormously on a world wide basis after World War II, primarily because of its effectiveness against the mosquitoes that spreads malaria and other insects which damages crops..
(ii) However, problems related to extensive use of DDT began to appear in the late 1940 s. Many species of insects developed resistance to DDT, it was also discovered to have a high toxicity towards fishes. DDT is not metabolised very rapidly by animals, instead it is deposited and stored in the fatty tissues. If the ingestion continues at a steady rate, DDT builds up within the animals overtime.
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