Determine the mass of water to be added to 20 g of acetic acid solution with a mass fraction of 70%

Determine the mass of water to be added to 20 g of acetic acid solution with a mass fraction of 70% to obtain a solution of acetic acid with a mass fraction of 5%

1. Let’s find the mass of acetic acid in the first solution.

The mass fraction of a substance is determined by the formula:

W = m (substance): m (solution) × 100%,

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

m (substance) = (20 g × 70%): 100% = 14 g.

2. Find the mass of the solution, which must be for the mass fraction of the acid to become 5%.

m (solution) = (m (substance): W) × 100%;

m (solution) = (14g: 5%): 100% = 280g.

3. Find the mass of water to add.

m (solution) = m (substance) + m (water).

m (water) = m (solution) – m (substance).

m (water) = 280 g – 14 g = 266 g.

Answer: 266 g.