Percentage by mass = (mass of solute ÷ mass of solution) × 100
Mass of solution = mass of solute + mass of solvent
Measure the mass of the solute
Measure the mass of the solvent
Add the solute mass and solvent mass to get the total mass of the solution
Divide the mass of the solute by the mass of the solution
Multiply the result by 100
Express the answer as a percentage