How much water is required to prepare 200 g of 40% sodium chloride solution?

Let’s calculate the weight of the dissolved salt.

M salt = 200 x 0.4 = 80 grams;

Similarly, we find the weight of the solvent (water).

(In the calculations, we take the density of water equal to 1 gram / cm3).

M water (solvent) = 200 x 0.6 = 120 grams = 120 ml;

Let’s check. To do this, we sum up the masses of the components of the solution and obtain the weight of the solution in question.

80 + 120 = 200;