From 180 g of a 25% solution of the substance, 20 g of water was evaporated.

univerkov | January 3, 2021 | education

From 180 g of a 25% solution of the substance, 20 g of water was evaporated. Find the mass fraction of the substance in the newly obtained solution.

Given: m1 = 180 g; m2 = 160 g; W1 = 25%. Find W2
We consider the mass of the substance in the original solution:
m (substance) = 180 * 25/100 = 45 g.
Knowing the mass of the substance in the original solution, we can find its mass fraction in the evaporated solution:
W2 = (45/160) * 100 = 28.125%
Answer: the evaporated solution contains 28.125% of the substance.

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