Redox Reactions

Ozone is quantitatively determined by bubbling it through an excess of acidic potassium iodide solution, which liberates iodine. The liberated iodine is then titrated with sodium thiosulphate solution.

If 25.0 mL of the iodine-containing solution required 20.0 mL of 0.01 M sodium thiosulphate for complete titration, calculate the number of moles of ozone that reacted.