What mass of salt is needed to prepare 150 g of a solution with a mass fraction of sodium chloride of 5%?

The mass of the solution is 150 grams;

To find the mass of salt, it is necessary to multiply its mass fraction by the mass of the solution.

m salt = 150 x 0.05 = 7.5 grams;

To find the mass of water, subtract the mass of salt from the mass of the solution:

m of water = 150 – 7.5 = 142.5 grams;

Check: 142.5 + 7.5 = 150;