In the manufacture of ${\mathrm{NH}}_3$by Haber’s process, the condition which would give maximum yield is ${\mathrm{N}}_{2\left(\mathrm{g}\right)}+3{\mathrm{H}}_{2\left(\mathrm{g}\right)}\to 2{\mathrm{NH}}_{3\left(\mathrm{g}\right)}+\mathrm{Q}.\mathrm{Cal}$

For the reaction,

${\mathrm{N}}_{2\left(\mathrm{g}\right)}+3{\mathrm{H}}_{2\left(\mathrm{g}\right)}\to 2{\mathrm{NH}}_{3\left(\mathrm{g}\right)}+\mathrm{Q}.\mathrm{Cal}$

Volume is decreased in a forward direction. Hence, the formation of ${\mathrm{NH}}_3$ favors at low temperature and high pressure.