When dissolved in 270 g of water, potassium sulfate was obtained a solution with a mass fraction of 10%. The mass of dissolved K2SO4 is

Let the mass of added potassium sulfate be equal to x g. Then the mass of the resulting solution will be equal to (270 + x) g, and the mass fraction of potassium sulfate can be expressed as:
100% ∙ x / (270 + x) = 10%
x / (270 + x) = 0.1
10x = 270 + x
9x = 270
x = 30
Thus, the mass of potassium sulfate to be added is 30 g.

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