A solution is prepared by mixing 20.0 g of NaNO3 with 100. mL of water. What is the percentage mass of the solution?

Percentage by mass is the amount of a component in a mixture per 100 unit if mass of the total mixture. From the problem, we first need to convert the volume of water to mass by using the density of water of 1000 g/L. We calculate as follows:

Mass of water =.100 L (1000 g/L) = 100 g water

Total mass = 100 g + 20 g = 120 g

Percent mass = 20 / 120 x 100 = 16.67% NaNO3 solution