+ 16H + ——> 2Mn + + 8H O + 10CO (d) Hydrogen sulphide is oxidised, sulphur being precipitated: H S —> 2H + + S – 5S – + 2MnO + 16H + ——> 2Mn + + 8H O + 5S (e) Sulphurous acid or sulphite is oxidised to a sulphate or sulphuric acid: 5SO – + 2MnO – + 6H + ——> 2Mn + + 3H O + 5SO – (f) Nitrite is oxidised to nitrate: 5NO – + 2MnO – + 6H + ——> 2Mn + + 5NO – + 3H O . In neutral or faintly alkaline solutions: (a) A notable reaction is the oxidation of iodide to iodate: 2MnO – + H O + I – ——> 2MnO + 2OH – + IO (b) Thiosulphate is oxidised almost quantitatively to sulphate: 8MnO – + 3S O – + H O ——> 8MnO + 6SO – + 2OH (c) Manganous salt is oxidised to MnO ; the presence of zinc sulphate or zinc oxide catalyses the oxidation: 2MnO – + 3Mn + + 2H O ——> 5MnO + 4H + Note : Permanganate titrations in presence of hydrochloric acid are unsatisfactory since hydrochloric acid is oxidised to chlorine. Uses Uses Uses Uses Uses: Besides its use in analytical chemistry, potassium permanganate is used as a favourite oxidant in preparative organic chemistry. Its uses for the bleaching of wool, cotton, silk and other textile fibres and for the decolourisation of oils are also dependent on its strong oxidising power.
THE INNER TRANSITION ELEMENTS ( f -BLOCK) The f -block consists of the two series, lanthanoids (the fourteen elements following lanthanum) and actinoids (the fourteen elements following actinium). Because lanthanum closely resembles the lanthanoids, it is usually included in any discussion of the lanthanoids for which the general symbol Ln is often used. Similarly, a discussion of the actinoids includes actinium besides the fourteen elements constituting the series. The lanthanoids resemble