Exercise 1 Question 19
How is O3 estimated quantitatively?
Quantitatively, ozone can be estimated with the help of potassium iodide. When ozone is made to react with potassium iodide solution buffered with a borate buffer (pH 9.2), iodine is liberated. This liberated iodine can be titrated against a standard solution of sodium thiosulphate using starch as an indicator. The reactions involved in the process are given below.
2I- + H2O + O3 → 2OH- + I2 + O2
Iodide Ozone Iodine
Sodium Sodium
thiosulphate tetrathionate