Calculate the mass percent of a NaCl solution in which 140g of NaCl is dissolved in 4.50L of water at 25C (density = 0.997g/mL).

Mass percent is one way of expressing concentration of a solution. It is expressed as the mass of solute per mass of solution. For this case, mass percent is calculated as follows:

% mass = 140 g NaCl / (140 g NaCl + 4500 mL (0.997 g/mL)) x 100

% mass = 3.03 %