Find the mass fraction in the solution obtained by mixing 200 g of 5% and 400 g of 10% solutions.

1.Let’s find the mass of the substance in the first and second solution.

w = m (substance): m (solution) x 100%.

hence m (substance) = (m (solution) × w): 100%.

m (substance) 1 = (200 g × 5%): 100% = 10g.

m (substance) 2 = (400 g × 10%): 100% = 40g.

2.Let’s find the mass of the substance in the resulting solution:

m (substance) 3 = 10 g + 40 g = 50 g.

3.Let’s find the mass of the solution:

m (solution) 3 = m (solution) 1 + m (solution) 2.

m (solution) 3 = 200 g + 400 g = 600 g.

4. Let’s find the mass fraction of the substance in the resulting solution.

w = (50g: 600g) × 100% = 8.33%.