Calculate the mass of table salt required to prepare 800 g of a 40% solution of this salt.

Let’s find the masses of the constituent components of the solution.
This requires multiplying their mass fraction by the weight of the solution.
Find the weight of the dissolved salt.
M salt = 800 x 0.4 = 320 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 = 800 x 0.6 = 480 grams = 480 ml;
Let’s check. To do this, add the masses of the components of the solution and get the mass of the required solution.
480 + 320 = 800;