Calculate the mass of NaOH required to prepare 200 g of a 15% solution.

Let’s find the masses of the constituent components of the solution.

This requires multiplying their mass fraction by the weight of the solution.

Let’s calculate the weight of the dissolved alkali.

M alkali = 200 x 0.15 = 30 grams;

In the same way, 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 0.85 = 170 grams;

Let’s check. To do this, add the masses of the components of the solution and obtain the mass of the required solution.

170 + 30 = 200;