How many grams of water must be evaporated from 80 g of 6% salt solution to obtain a solution containing 10% salt?

We have 80 grams of 6% salt solution. The salt concentration tells us how many percent the salt is in the solution. Let’s find its quantity:

80 * 0.06 = 4.8 g of salt in solution.

The mass of salt remains unchanged, nothing is done with it. Changes occur only with the mass of water.

The same mass of salt is now 10% of the total mass of the solution. Let’s find it:

4.8: 0.1 = 48 g – the mass of the new solution.

The mass of water in the new solution is:

48 – 4.8 = 43.2 g.

In the old solution, the mass of water was:

80 – 4.8 = 85.2 g.

Then the mass of water to be evaporated is equal to:

85.2 – 43.2 = 42 g of water.