Question

Give the balanced equation for the laboratory preparation of an unsaturated hydrocarbon from alcohol.

Answer 1

Laboratory preparation of an unsaturated hydrocarbon from alcohol.

• Alkenes (unsaturated hydrocarbons with double bonds) are prepared in the laboratory by dehydration of alcohol.
• Ethene$\left(C_2{H}_4\right)$ is prepared by heating Ethanol$\left(C_2{H}_{5}OH\right)$ with an excess of concentrated Sulphuric acid $\left(H_{2}S{O}_4\right)$ at a temperature of $160°C-170°C$.
• The gas is passed through a wash bottle and pure ethene is collected by downward displacement of water.
• The chemical equation is:

$\underset{\left(\mathrm{Ethanol}\right)}{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\left(\mathrm{l}\right)}\stackrel{\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }\underset{\left(\mathrm{Ethene}\right)}{{\mathrm{C}}_2{\mathrm{H}}_4}\left(g\right)+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$