Catalysts in the following reactions are

I) ${\mathrm{CH}}_3{\mathrm{COOCH}}_3\left(\mathrm{l}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)+{\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{l}\right)$

II) $2{\mathrm{SO}}_2\left(\mathrm{g}\right)\to 2{\mathrm{SO}}_3\left(\mathrm{g}\right)$

III) $2{\mathrm{SO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{SO}}_3\left(\mathrm{g}\right)$

IV) ${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\to 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$

Acidic hydrolysis is simply the reverse of esterification. The ester is heated with a large excess of water containing a strong-acid catalyst. Platinum was the catalyst used in the conversion of sulphur dioxide to sulphur trioxide. Chamber process, also called Lead-chamber Process, method of producing sulfuric acid by oxidizing sulfur dioxide with moist air, using gaseous nitrogen oxides as catalysts. The catalyst used in Haber's process in a metal catalyst, iron. Iron has been preferred because it helps to achieve an acceptable yield of a product in a much faster time.