Question

You wish to add 5 mg/l naocl as cl2 to a solution in a disinfection test, and you have a stock solution (household bleach) that contains 5% naocl by weight. assuming that the density of the stock solution is 1.0 g/ml, how many milliliters of bleach should you add to each liter of test solution?

Answer 1

Answer: -

0.1 ml of bleach should be added to each liter of test solution.

Explanation:-

Let the volume of bleach to be added is B ml.

Density of stock solution = 1.0 g/ml

Mass of stock solution = Volume of stock x density of stock

                                     = B ml x 1.0 g/ml

                                     = B g

Amount of NaOCl in this stock solution = 5% of B g

                                     = $\frac{5}{100}$ x B g

                                     = 0.05 B g

Now each test solution must be added 5 mg/l NaOCl.

Thus each liter of test solution must have 5 mg.

Thus 0.05 B g = 5 mg

                        = 0.005 g

B = $\frac{0.005}{0.05}$

  = 0.1

Thus 0.1 ml of bleach should be added to each liter of test solution.