In 180 g of water, 20 g of salt is dissolved. determine the mass fraction of salt in the solution.

Answer: 10%.
Explanation of the solution to the problem: to solve this problem, you must use the following formula:
w = m (solv.v-va) / m (solution), where w is the mass fraction of the solute in the solution, m (solv.v-va) is the mass of the solute (in this case, it is the mass of salt), m (solution) – the mass of the solution.
m (solution) = m (solution in-va) + m (water).
Substituting sequentially all the values in the formulas, we get:
m (solution) = m (solution in-va) + m (water) = 20 + 180 = 200 g.
w = m (solution in-va) / m (solution) = 20/200 * 100% = 10%.