To 100 g of a salt solution with a mass fraction of salt of 40%, 20 g of salt was added.

To 100 g of a salt solution with a mass fraction of salt of 40%, 20 g of salt was added. Determine the concentration of the resulting solution in mass fractions.

Given:

m1 (solution) = 100 g.

w1 (salt) = 40% = 0.4.

m3 (salt) = 20 g.

To find:

w2 (solution) -?

Solution:

m1 (salt) = m1 (solution) * w1 (salt) = 100 g * 0.4 = 40 g.

m2 (solution) = m1 (solution) + m3 (salt) = 100 g + 20 g = 120 g.

m2 (salt) = m1 (salt) + m3 (salt) = 40 g + 20 g = 60 g.

w2 (salt) = m2 (salt): m2 (solution) * 100% = 60: 120 * 100% = 0.5 * 100% = 50%.

Answer: w2 (salts) = 50%.