# Another 5 g of sodium chloride was dissolved in 160 g of a 12% sodium chloride solution. What is the mass fraction

Another 5 g of sodium chloride was dissolved in 160 g of a 12% sodium chloride solution. What is the mass fraction of salt in the resulting solution? Given: m (solution) = 160 g, ω (NaCl) = 12%, or 0.12, m1 (NaCl) = 5 g.
Find: ω2 (NaCl) -?
Decision.
1. Find the mass of the solute (NaCl) in the initial solution:
m (NaCl) = m (solution) • ω (NaCl) = 160 g • 0.12 = 19.2 g.
2. Find the mass of the solute (NaCl) in the resulting solution:
m2 (NaCl) = m (NaCl) + m1 (NaCl) = 19.2 g + 5 g = 24.2 g.
3. Find the mass of the resulting solution:
m2 (solution) = m (solution) + m2 (NaCl) = 160 g + 5 g = 165 g.
4. Find the mass fraction of the solute (NaCl) in the resulting solution:
ω2 (NaCl) = m2 (NaCl) / m2 (solution a) = 24.2 g: 165 g = 0.147, or,
multiplying this value by 100%, we get 14.7%. Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.