To 250 g of a 10% solution of sodium nitrate was added 10 g of the same salt and 50 ml. water. What is the mass fraction of sodium nitrate in the resulting solution?
Find the mass of salt m = 250 * 0.1 + 10 = 35 g
Find the mass of the final solution m (solution) = 250 + 10 + 50 = 310 g
ω = m (substance) / m (solution) = 35 * 100/310 = 11.3%
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