Describe two methods of preparaton of ethane. Given any three reaction of ethane.

Explanation

Methods of preparation of ethane :
1. Decarboxylation of sodium propionate : Ethane is prepared by heating sodium propionate with soda lime. (Soda lime = NaOH + CaO)
`CH_(3) - CH_(2) - COONa + NaOH underset(Delta)overset(CaO)(rarr) C_(2)H_(6) + Na_(2)CO_(3)`
2. Wurtz reaction : Ethane is prepared by heating methyl iodide with sodium metal in dry ether.
`CH_(3)I + 2Na + ICH_(3) underset("ether")overset("Dry")(rarr) CH_(3) - CH_(3) + 2NaI`
Properties of ethane :
1. Substitution reactions : Reactions in which an atom or group present in a compound is replaced by another atom or group are known as substitution reactions.
(a) Halogenation : In the presence of sunlight or UV radiation ethane undergoes halogenation. The H atoms of alkane are successively replaced by the halogen atoms.
`C_(2)H_(6) underset(Cl_(2))overset(hv)(rarr) C_(2)H_(5)Cl underset(Cl_(2))overset(hv)(rarr) C_(2)H_(4)Cl_(2) underset(Cl_(2))overset(hv)(rarr)C_(2)H_(3) Cl_(3) underset(Cl_(2))overset(hv)(rarr) C_(2)H_(2)Cl_(4) underset(Cl_(2))overset(hv)(rarr)C_(2)HCl_(5) underset(Cl_(2))overset(hv)(rarr) C_(2)Cl_(6)`
(b) Nitration : Ethane reacts with vapours of `HNO_(3)` at `400^(@)C` and forms nitroethane.
`C_(2)H_(6) + HNO_(3) overset(400^(@)C)(rarr) C_(2)H_(5)NO_(2) + H_(2)O`
(2) Combustion : Complete oxidation of the compound in air is called .combustion.. It gives `CO_(2) and H_(2)O` along with liberation of heat.
`C_(2) H_(6) + (7)/(2) O_(2) rarr 2CO_(2) + 3H_(2)O` + energy