Describe two methods of preparation of ethylene . Give equation for the reactions of ethylene with the
Heated with `O _(2)` at high pressure

Explanation

Preparation of enthalene :
1. Dehydrohalogenation of alkyl hallde: When ethyl beomides is heated with alcoholic KOH. Ethylene is formed.
`underset("Ethyl bromide") ( CH_(3) CH _(2) Br + KOH) overset( "Alcoholic KOH") to H _(2) C = underset( " Ethylene") ( CH_(2) + KBr + H _(2) O )`
2. Dehydration of ethanol: When ethanol is heated with conc. `H _(2) SO_(4)` at `170^(@)C,` ethylene is obtained.
`H - underset( " Ethanol") underset(H) underset(|) overset(H) overset(|) (C) - underset( H) underset(|) overset(OH) overset(|) (C) - H overset(conc. H _(2) SO _(4)) underset(170^(@)C) to underset("Ethylene") ( H _(2) C = CO _(2) + H_(2)O)`
Polymerisation: When Ethylene is heated in the presence of `O_(2)` at temperature of `200^(@)C ` and highe pressure of `1500 - 2000` atmospheres gives polyethane.
`underset( " Ethylene") (n CH _(2) = CH)overset( O _(2) // 200^(@)C) underset( 1500- 2000 atm)tounderset("Polythene") ((C _(2) H _(4)) _(n))`