Mass fraction is the ratio of the mass of the solute to the total mass of the solution. It is expressed as a percentage of the total mass of the solution: w = (m / M), where w is the mass fraction, m is the mass of the solute (g), M is the total mass of the solution (g).
So, the mass fraction of salt in the solution = 0.4, or 40%. This means that the same solution weighing 100 g contains 40 g of salt: 0.4 * 100 = 40 (based on the formula above). Knowing the salt content in 100 g of solution, we can calculate the mass of salt in 250 g of solution:
100 g solution – 40 g salt
250 g of solution – x g of salt. x = (250 * 40) / 100 = 100 g of salt.
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