To 200 g of a 15% sodium chloride solution was added 25 g of sodium chloride.

To 200 g of a 15% sodium chloride solution was added 25 g of sodium chloride. calculate the mass fraction of sodium chloride in the resulting solution.

Given:
m1 solution (NaCl) = 200 g
ω1 (NaCl) = 15%
m2 (NaCl) = 25 g

To find:
ω3 (NaCl) -?

1) m1 (NaCl) = ω1 * m1 solution / 100% = 15% * 200/100% = 30 g;
2) m3 (NaCl) = m1 + m2 = 30 + 25 = 55 g;
3) m3 solution (NaCl) = m1 solution + m2 = 200 + 25 = 225 g;
4) ω3 (NaCl) = m3 * 100% / m3 solution = 55 * 100% / 225 = 24%.

Answer: The mass fraction of NaCl is 24%.