To 165 g of a 20% salt solution, 45 g of water was added. Determine the mass fraction of salt in the resulting solution.

Given:

m (solution) = 165 grams;

w% (salt) = 20%;

m (H2O) = 45 grams;

Find:

w% (salts in the final solution) -?

Solution:

1) Find the mass of the final solution after adding water:

m (solution) = 165 g + 45 g = 210 g;

2) Find the mass of salt in the initially given solution:

m (salt) = 165 g * 0.2 = 33 g;

3) Find the mass fraction of salt in the resulting solution:

w% (salts in the final solution) = m (salts): m (solution) * 100% = 33 g: 210 g * 100% = 15.7%.

Answer: w% (salts in the resulting solution) = 15.7%.