Question: how to calculate mass by volume percentage of a solution?
Answer: Convert the units (mass in grams, volume in mL): mass KCl = 45.0g. volume of solution = 2.0 L = 2.0 L × 103 mL/ L = 2000 mL.
Calculate w/v (%) w/v (%) = [mass solute (g) ÷ volume solution (mL)] × 100. Substitute in the values and solve: w/v (%) = [45.0 ÷ 2000 mL] × 100 = 2.25 g/100mL (%)