1.

How is O_3 estimated quantitatively?

Answer»

Solution :When `O_3` is treated with excess of KI solution BUFFERED with borate buffer (pH 9.2), `I_2` is liberated QUANTITATIVELY, according to the following equation:
`2I^(-) (aq) + H_2O (l) + O_3 (G) to 2OH^(-) (aq) + I_2(s) + O_2 (g)`
The `I_2` thus liberated is titrated against a standard solution of sodium thiosulphate USING starch as an indicator .
`underset("Sodium thiosulphate")(2Na_2S_2O_3) + I_2 to Na_2S_4O_6 + underset("Sodium tetrathionate")(2NaI)`
Quantitative estimation of `O_3` is thus carried out.


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