To 110 g of a solution with a mass fraction of magnesium chloride 10% was added 21 ml of water and 21 g of the same salt. Mass fraction of salt in the resulting solution is equal to
ω = m (substance) / m (solution)
Find the mass of the substance m = 110 * ω + 21 = 32 g
Find the mass of the solution m = m (initial) + m (added) = 110 + 21 + 21 = 152 g
ω (final) = 32 * 100/152 = 21%
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