Question

How is ozone prepared?

Answer 1

A silent electric discharge in dry, pure dioxygen is used to create ozone.

\[\ce{3O2 <=>[\underset{discharge}{Silent electric}] 2O3}\]; ΔH = +285.4kJ

One mole of ozone is formed by the endothermic reaction, which requires the absorption of \[\ce{\frac{285.4}{2}}\] = 142.7 kJ of energy.

Since the silent electric discharge, also known as the sparkless electric discharge, generates less heat, it stops the local temperature from rising; otherwise, the ozone created during the reaction will break down back into oxygen.

The apparatus used to create ozone is known as an ozoniser. The two most often used ozonisers are Brodie’s and Siemen’s.