Question

Outline, how the following substances can be obtained:

(a) Ethene from ethanol

(b) Ethanol from ethene

Answer 1

(a) Ethene from ethanol

• Ethene (${\mathrm{CH}}_2={\mathrm{CH}}_2$) is a hydrocarbon that comes under the Alkenes group because it has a double bond.
• Ethanol (${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$) is a hydrocarbon in which two Carbon ($\mathrm{C}$) atoms are present and the functional group is Hydroxyl group ($-\mathrm{OH}$).
• We can convert Ethanol (${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$) to Ethene by treating the Ethanol with Concentrated Sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$) at a temperature of $443\mathrm{K}$. The reaction is given below:

$\underset{\mathrm{Ethanol}}{{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}}\left(l\right)\underset{443\mathrm{K}}{\overset{\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}\underset{\mathrm{Ethene}}{{\mathrm{CH}}_2={\mathrm{CH}}_2\left(g\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

• This reaction is also known as the Dehydration reaction.

(b) Ethanol from ethene

• When Ethene reacts with Water in the presence of an acid, it will convert into Ethanol.
• The reaction is given below:

$\underset{\mathrm{Ethene}}{{\mathrm{CH}}_2={\mathrm{CH}}_2}\left(g\right)+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\stackrel{{\mathrm{H}}^{+}}{\to }\underset{\mathrm{Ethanol}}{{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}\left(l\right)}$

This reaction is also known as the Hydration reaction.