100 ml of solution contains 20 g of sodium hydroxide. The density of the solution is 1.2 g / mol.

100 ml of solution contains 20 g of sodium hydroxide. The density of the solution is 1.2 g / mol. Determine the percentage concentration of the solution.

Sodium hydroxide: NaOH.
Working formula: W = (m.w / mr-ra) * 100%.
1) Find the mass of the sodium hydroxide solution. The mass fraction is found by multiplying the volume of the solution by its density: 100 * 1.2 = 120g.
2) The mass of the solute is 20g.
3) Find the mass fraction of the substance in the solution. Let’s use a working formula. We divide the mass of the solute by the mass of the solution and multiply it by one hundred percent: 20/120 * 100 = 16.7%.
Answer: the mass fraction of sodium hydroxide substance in the solution is 16.7%.