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Methods of analyses

I am looking for a method for analyses to NaOCl,if you know any method please tell me.

Paulo SÈrgio Martins Alvares
- Londrina, Pr, Brazil
2001

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2001

Senhor Martins Alvares,

You should dissolve 0.5 g of soluble starch in 5 ml of cold demi water and add 95 ml of boiling water (add 0.1 soln of salicilic acid as preserver). As titrating agent you should use sodium thiosulphate ⇦this on eBay or Amazon [affil links] 0.1N. 25 ml of NaOCl are diluted to 1000 ml. 25 ml of this solution are put in a 250 ml flask, containing 50 ml of water, 20 ml of KJ (Potassium iodide) 10% and 10 ml of conc. acetic acid ⇦this on eBay or Amazon [affil links] (keep the 25 ml pipette [pipettes on eBay or Amazon [affil links] tip slightly immerse into the solution). Titration follows: when solution colour changes from dark brown to light yellow, add 1 ml of starch solution. Titration ends when the blue colour disappears.

Results

Active Chlorine (g Cl/litre) = (ml thiosulphate*0.1*35.46)/0.625 where 0.625 is the actual NaOCl employed

Best regards

Francesco Cicchetti
- Sulmona, Italy