Merged two solutions of hydrochloric acid: 200 g of 15% and 50 g of 5%. What is the mass fraction

Merged two solutions of hydrochloric acid: 200 g of 15% and 50 g of 5%. What is the mass fraction of acid in the resulting solution?

The mass fraction of the substance contained in the solution is found by the formula:

ω = m (in-va): m (solution) * 100%.

From here
m (in-va) = ω * m (solution): 100%.

Let’s calculate the mass of the substance in the first solution:

m (in-va) = 15 * 200: 100 = 30g.

The mass of the substance in the second solution:

m (in-va) = 5 * 50: 100 = 2.5g.

The mass of the substance in the resulting solution:

m (in-va) = 30 + 2.5 = 32.5 g.

Then the mass fraction of the substance in the resulting solution:

ω = 32.5: 250 * 100% = 13%.

Answer. Mass fraction of acid in the resulting solution is 13%.