From 280 g of a 25% solution of some salt, 32.9 g of precipitate was released upon cooling.

From 280 g of a 25% solution of some salt, 32.9 g of precipitate was released upon cooling. What is the mass fraction of salt in the remaining solution?

1. Let’s find the total mass of salt in the solution:

m (salt) = 280 * 25/100 = 70g.

2. Find the mass of water in the solution:

m (H2O) = 280 – 70 = 210g.

3. Find the mass of salt after precipitation:

m (salt) = 70 – 32.9 = 37.1g.

4. Find the mass of the resulting solution:

m (solution) = 210 + 37.1 = 247.1 g.

5. Find the mass fraction of salt in the remaining solution:

ω (salt) = 37.1 / 247.1 * 100 = 15%.