Homogeneous Catalysis

In homogeneous catalysis, the reactants and the catalyst are all present in the same phase. Four examples are given. (i) The iodide ion (I-) catalyses the decomposition of aqueous hydrogen peroxide -- both I- and H2O2 are dissolved in the same aqueous phase. (ii) Nitric oxide catalyses the oxidation of sulfur dioxide to sulfur trioxide by dioxygen in the lead chamber process: 2 SO2(g) + O2(g) --[NO(g)]--> 2 SO3(g), with reactants and catalyst all in the gas phase. (iii) The hydrolysis (inversion) of sucrose is catalysed by the H+ ion supplied by sulfuric acid: C12H22O11(aq) + H2O(l) --[H2SO4]--> C6H12O6(aq) [glucose] + C6H12O6(aq) [fructose], with the acid catalyst dissolved in the same aqueous solution as the sugar. (iv) Enzyme catalysis, where a biological enzyme dissolved (or dispersed) in the same medium as its substrate speeds up a biochemical reaction, is also classed as an important type of homogeneous catalysis. In every one o …