200 g of a 6% salt solution was evaporated until the mass fraction of the salt was 20 percent.

200 g of a 6% salt solution was evaporated until the mass fraction of the salt was 20 percent. What mass of water has evaporated?

The mass of the solution is 200 g.

Mass fraction is equal to 6%.

The mass fraction of the resulting solution is 20%.

Let’s determine the mass of water that has evaporated.

First you need to determine the mass of the salt.

W = m r.v / m r-ra * 100%.

m (salt) = 200 * 6/100 = 12 g.

Next, we determine the mass of the resulting solution. Let us denote the mass of the solution through x.

12 / x * 100 = 20.

X = 12 * 100/20 = 60 g.

Let’s determine the mass of water that has evaporated. To do this, subtract from the initial mass of the solution the mass of the salt and the mass of the solution that turned out.

200 – 60 – 12 = 128 g.

Answer: the mass of water is 128 g.