The strength of bleaching powder is given as the percentage of available chlorine, which is the…

The strength of bleaching powder is given as the percentage of available chlorine, which is the mass of chlorine that releases the same amount of iodine from iodide as the sample does. A sample of $2.54\ \text{g}$ of bleaching powder is made up to $250\ \text{mL}$ of solution. A volume of $25.0\ \text{mL}$ of the solution is added to an excess of acidified potassium iodide. The reactions are $\text{OCl}^- + 2\text{I}^- + 2\text{H}^+ \rightarrow \text{Cl}^- + \text{I}_2 + \text{H}_2\text{O}$ and $\text{I}_2 + 2\text{S}_2\text{O}_3^{2-} \rightarrow 2\text{I}^- + \text{S}_4\text{O}_6^{2-}$. The liberated iodine needs $22.9\ \text{mL}$ of $0.100\ \text{mol/L}$ sodium thiosulphate. One mole of chlorine liberates one mole of iodine, and its molar mass is $71.0\ \text{g/mol}$. Find the iodine in the portion, the chlorine equivalent of the whole sample and the percentage of available chlorine.