From 500 g of a 30% NaCl solution, 150 g of water was removed by evaporation.

From 500 g of a 30% NaCl solution, 150 g of water was removed by evaporation. What is the% concentration in the remaining solution?

Given:
m1 solution (NaCl) = 500 g
ω1 (NaCl) = 30%
m (H2O) = 150 g

Find:
ω2 (NaCl) -?

1) m1 (NaCl) = ω1 * m1 solution / 100% = 30% * 500/100% = 150 g;
2) m2 (NaCl) = m1 (NaCl) = 150 g;
3) m2 solution (NaCl) = m1 solution (NaCl) – m (H2O) = 500 – 150 = 350 g;
4) ω2 (NaCl) = m2 * 100% / m2 solution = 150 * 100% / 350 = 43%.

Answer: The mass fraction of NaCl is 43%.