In water, mass of which = 300 g, salt was dissolved, mass of which = 75 g. Calculate the mass fraction of salt in the solution (%).

Mass fraction is denoted by w.

Let’s take the formula for finding the mass fraction: w (X) = m (X): m (X) + m (Y) * 100%.

Multiplication by 100 is needed in order to get the answer as a percentage.

Let’s take table salt – NaCl as salt, because the most familiar and common.

w (NaCl) = m (NaCl): m (solution) * 100% = m (NaCl): (m (H2O) + m (NaCl)) * 100% – the formula for a specific task.

Substitute the values: w (NaCl) = 75: (300 + 75) * 100% = 75: 375 * 100% = 0.2 * 100% = 20%.