To 100 g of sodium chloride solution, a mass fraction of 40% was added 55 g.

To 100 g of sodium chloride solution, a mass fraction of 40% was added 55 g. Water, what is the mass fraction of salt in the resulting solution?

Given:
m1 solution (NaCl) = 100 g
ω1 (NaCl) = 40%
m (H2O) = 55 g

To find:
ω2 (NaCl) -?

1) m1 (NaCl) = ω1 * m1 solution / 100% = 40% * 100/100% = 40 g;
2) m2 (NaCl) = m1 (NaCl) = 40 g;
3) m2 solution (NaCl) = m1 solution (NaCl) + m (H2O) = 100 + 55 = 155 g;
4) ω2 (NaCl) = m2 * 100% / m2 solution = 40 * 100% / 155 = 26%.

Answer: The mass fraction of NaCl is 26%.