(a) Ethene when reacts with halogens (chlorine and bromine) form saturated products. Name them and write balanced equations.

(b) Give the conditions and the main product formed by hydrogenation of ethene.

(a)

$\underset{\text{ ethene}}{\text{C}$2\text{H}4} + \text{Cl}2 \xrightarrow[\text{[inert solvent]}]{\text{CCl}4} \underset{\text{1,2, dichloroethane [ethylene chloride]}}{\text{C}2\text{H}4\text{Cl}_2}

Product formed is 1,2, dichloroethane [ethylene chloride]

$\underset{\text{ ethene}}{\text{C}$2\text{H}4} + \text{Br}2 \xrightarrow[\text{[inert solvent]}]{\text{CCl}4} \underset{\text{1,2, dibromooethane [ethylene bromide]}}{\text{C}2\text{H}4\text{Br}_2}

Product formed is 1,2, dibromooethane [ethylene bromide]

(b) Conditions for hydrogenation of ethene : finely divided catalyst, such as platinum or palladium at ordinary temperature or nickel at 200°C. Main product formed is ethane.

$\underset{\text{ ethene}}{\text{C}$2\text{H}4} + \text{H}2 \xrightarrow[200\degree\text{C}]{\text{Nickle}} \underset{\text{ethane}}{\text{C}2\text{H}_6}