# 120 g of a solution with a mass fraction of 10% was evaporated to 80 g. What is the mass fraction of salt in one stripped off solution.

August 22, 2021 | education

| Given:

w1 (solution) = 10%

m1 (solution) = 120 g

m2 (solution) = 80 g

Need to know: w2 (solution)

Solution:

To begin with, we calculate the mass of a soluble substance contained in 120 g of a 10% solution: m1 (solutions) = m1 (solution) ∙ w1 (solution) / 100% = 120 g ∙ 10% / 100% = 12 g

let’s calculate the concentration of the solution, taking into account the evaporation of the solution up to 80g:

w2 (solution) = m2 (solution) ∙ 100% / m2 (solution) = 12g * 100% / 80g. = 15%

Answer: w2 (solution) = 15%

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