Percent mass question/molarity question

Express the concentration of a 0.0790 M aqueous solution of fluoride, F–, in mass percentage and in parts per million. Assume the density of the solution is 1.00 g/mL.

How do you actually solve it?

ppm = mg/kg.

0.0790 M = 0.0790 mol/L = 0.0790 mol/kg

(since 1 mL = 1 g so 1L = 1 kg).

mass = moles x atomic mass

= 0.0790 mol x 18.998 g/mol = 1.5 g = 1500 mg.

1500 mg/kg = 1500 ppm F-.= 0.15%.(m/m).