What masses of salt and water do you need to take to prepare 500 g of a 20 percent solution?

We work according to the formula ω = m substance / m solution * 100%, where ω is the mass fraction.

We need to find the mass of a substance, for this we transform the formula: m substance = ω * m solution / 100%.

Then m substance = 100 g.

Let us find the mass of H2O, for this we subtract m of the substance from the m solution: 500 g – 100 g = 400 g.

Answer: m substance = 100 g; m H2O = 400 g.