Question

5.00 ml of commercial bleach was diluted to 100.0 ml. 25.0 ml of the diluted sample was titrated with 4.56 ml of 0.100 m s2o3 2- . what is the concentration of hypochlorite in the original bleach solution? assume the density of the commercial bleach is 1.08 g/ml. calculate the average percent by mass of naclo in the commercial bleach.

Answer 1

The solution would be like this for this specific problem:

 

4 NaOCl + S2O3{2-} + 2 OH{-} → 2 SO4{2-} + H2O + 4 NaCl

(0.00456 L) x (0.100 mol/L S2O3{2-}) x (4 mol NaOCl / 1 mol S2O3{2-}) x (100.0 mL / 25 mL) x 
(74.4422 g NaClO/mol) = 0.54313 g 

(5.00 mL) x (1.08 g/mL) = 5.40 g solution 

(0.54313 g) / (5.40 g) = 0.101 = 10.1%

 

So, the average percent by mass of NaClO in the commercial bleach is 10.1%.