After complete evaporation of 50 g of the solution, 6 g of a solid residue was formed.

After complete evaporation of 50 g of the solution, 6 g of a solid residue was formed. The mass fraction of the solute in the taken solution was?

Given:
m solution (substance) = 50 g
m (substance) = 6 g

To find:
ω (substances) -?

Decision:
When evaporated, water leaves the solution, and the solute precipitates.
1) Calculate the mass fraction of the substance in the original solution:
ω (substances) = m (substances) * 100% / m solution (substances) = 6 * 100% / 50 = 12%.

Answer: The mass fraction of the substance in the original solution was 12%.