→ 4S – (aq) + 2S O – (aq) + 6H O(l) ( . ) + – Cl (g) + OH – (aq) → ClO – (aq) + Cl – (aq) + H O (l) ( . ) The reaction ( . ) describes the formation of household bleaching agents.
The hypochlorite ion (ClO – ) formed in the reaction oxidises the colour-bearing stains of the substances to colourless compounds. It is of interest to mention here that whereas bromine and iodine follow the same trend as exhibited by chlorine in reaction ( . ), fluorine shows deviation from this behaviour when it reacts with alkali. The reaction that takes place in the case of fluorine is as follows: F (g) + 2OH – (aq) → F – (aq) + OF (g) + H O(l) ( .
) (It is to be noted with care that fluorine in reaction ( . ) will undoubtedly attack water to produce some oxygen also). This departure shown by fluorine is not surprising for us as we know the limitation of fluorine that, being the most electronegative element, it cannot exhibit any positive oxidation state. This means that among halogens, fluorine does not show a disproportionation tendency.
Problem . Which of the following species, do not show disproportionation reaction and why ? ClO – , ClO – , ClO – and ClO – Also write reaction for each of the species that disproportionates. Among the oxoanions of chlorine listed above, ClO – does not disproportionate because in this oxoanion chlorine is present in its highest oxidation state that is, + .
The disproportionation reactions for the other three oxoanions of chlorine are as follows: + – + 3ClO – → 2Cl – + ClO – + + – ClO – 4ClO – + 2Cl – + – + 4ClO – → Cl – + ClO – Problem . Suggest a scheme of classification of the following redox reactions (a) N (g) + O (g) → NO (g) (b) 2Pb(NO )