% active chlorine is an unit of focus employed for hypochlorite-based bleaches. One gram of a 100percent active chlorine bleach has got the exact same bleaching energy together gram of chlorine. The word "active chlorine" is employed because most commercial bleaches have considerable quantities of chlorine in the shape of chloride ions, without any bleaching properties.
Fluid bleaches offered for domestic use are typically 3–10per cent energetic chlorine, and should be diluted to 1–2per cent energetic chlorine before use. Commercial domestic bleaching powder is typically about 40% energetic chlorine. Values for a few commercial solid bleaches receive inside table below.
Values can be greater than 100% because hypochlorite ion have greater oxidation condition (+1) than chlorine(0) so high oxidation power .
Per Cent active chlorine values have finally practically changed the older system of chlorometric levels: 1% active chlorine is the same as 3.16 °Chl. Taking the (fair) assumption that energetic chlorine contained in a liquid bleach is in the kind of hypochlorite ions, 1percent active chlorine is equivalent to 0.141 mol/kg ClO−(0.141 mol/L whenever we believe density=1). For a good bleach, 100percent energetic chlorine is equivalent to 14.1 mol/kg ClO−: lithium hypochlorite has a molar mass of 58.39 g/mol, equivalent to 17.1 mol/kg or 121percent energetic chlorine.
Active chlorine values are usually dependant on incorporating an excess of potassium iodide to a sample of bleach solution and titrating the iodine liberated with standard sodium thiosulfate solution.Cl2 + 2I− → I2 + 2Cl−
orClO− + 2I− + 2 H+ → I2 + H2O + Cl−
then2S2O32− + I2 → S4O62− + 2I−