From 250 g of 20% potassium chloride solution, 100 ml of water was evaporated.

From 250 g of 20% potassium chloride solution, 100 ml of water was evaporated. What is the mass fraction of salt in the solution?

1. Let’s find the mass of KCl:

m (KCl) = m (KCl solution) * ω1 (KCl) = 250 * 0.2 = 50g.

2. Let’s find the mass of water:

m (H2O) = V (H2O) * P (H2O) = 100 * 1 = 100g.

3. Find the mass of the KCl solution:

m (KCl solution) = m (first KCl solution) – m (H2O) = 250 – 100 = 150g.

4. Find the mass fraction of KCl in the solution:

ω (KCl) = m (KCl) / m (KCl solution) = 50/150 = 0.333 (33.3%).

Answer: ω (KCl) = 33.3%.