This has the effect of increasing the
concentration of the reactants at the catalyst surface and also weakening
of the bonds in the reacting molecules (the activation energy is lowering) Also because the transition metal ions can change their oxidation states,
they become more effective as catalysts For example, iron(III) catalyses
the reaction between iodide and persulphate ions 2 I
– + S2O8
2– ® I2 + 2 SO4
2–
An explanation of this catalytic action can be given as:
2 Fe
3+ + 2 I
– ® 2 Fe
2+ + I2
2 Fe
2+ + S2O8
2– ® 2 Fe
3+ + 2SO4
2–
Interstitial compounds are those which are formed when small atoms
like H, C or N are trapped inside the crystal lattices of metals