(ii) There are millions of organic compounds.
Answer. The ability of carbon atom to link with other carbon atom to link with other carbon atom to form long chain, large rings in an organic compound. The compounds of carbon display catenation. So they form large number of organic compounds. They are present in basic skeleton of all living things.
(iii) Acetylene undergoes addition reactions in two stages.
Answer. In addition reaction first triple bond is changed to double bond and again double bond changes to single bond. That is the reason acetylene undergoes addition reactions in two stages. For example, hydrogenation of acetylene
HC≡CH + H2 250-300 C H2C=CH2
H2C=CH2 + H2 250-300 C H3C-CH3
(iv). Alkynes are more reactive than alkanes
Answer. Alkynes are reactive compounds because of presence of a triple bond. A triple bond consists of two weak bonds and a strong bond. When alkynes react with other substances, two weak bonds are readily broken one by one and addition takes place easily. In case of alkanes only sigma bonds are present which are strong and are not
easily broken. Sigma bond is not broken in simple addition reactions.
- No.7. Explain the different uses of hydrocarbons in industry.
Answer. Hydrocarbons are not only used as fuel in auto-mobiles or industries; they are also used as raw materials in industries. It is explained as
(i) Petrochemical Industry: The organic compounds prepared from hydrocarbons (petroleum and natural gas) are called petrochemicals. Some of the important petrochemicals are methyl alcohol, ethyl alcohol, methanoic acid, chloroform, carbon tetrachloride, ethylene, butadiene, benzene, toluene etc.
(ii) Plastic Industry: Hydrocarbons are used as raw materials for the preparation of a large variety of items used in daily life. Such as, plastics like polythene, polyester. Plastics are synthetic materials which can be given any shape when soft, and on hardening make a useful durable article. For example, crockery items (cups, glass, jug, plates, spoon) furniture items (chair, table, stool) auto-mobile parts, electric and sewages items and a lot of other house hold items.
(iii) Rubber Industry: Hydrocarbons are used to prepare synthetic rubber. For example, acetylene is used to prepare butadiene rubber used for making foot wear, tyres and toys. Similarly a good quality rubber neoprene is prepared from chloroprene.
(iv) Synthetic fiber Industry: Hydrocarbons are used to prepare synthetic fibers like nylon, rayon, polyesters. These fibers have better qualities like greater strength, good elasticity, and resistance to wear and tear. So clothes made of synthetic fibers are long lasting than that of natural fibers,
(v) Synthetic detergents: Long chain hydrocarbons obtained from petroleum are used to make synthetic detergents and washing powders. These detergents have long chain of alkyl hydrogen sulphate. These detergents have better and stronger cleaning properties than that of soaps. They can be used even in hard water.