From 500 g of 15 percent of the solution, 100 ml of water was evaporated.

From 500 g of 15 percent of the solution, 100 ml of water was evaporated. Calculate the mass fraction of p. substances. in solution after evaporation.

Since the density of water is approximately equal to 1 g / ml, then V (water) = m (water)

m (solution) = 500 g. This includes m (water) + m (substance).

m (in-va) = 0.15 * 500 = 75 grams.

m (water) = 500 – 75 = 425 grams.

We evaporated 100 grams of water: m (solution) = 425 – 100 + 75 = 400 grams.

Let’s make the proportion:

400 grams = 100%,

75 grams (substance) = x%.

75 * 100/400 = 18.75 grams.