Commercial perchloric acid is 70.0% by mass, HClO₄(aq), and has a density of 1.67 g/mL. Calculate the mole fraction of perchloric acid in the solution.

Question

Quizplus · Accepted Answer

To find the mole fraction, calculate moles of HClO4 and water in 100 g of solution. 70 g HClO4 (molar mass = 100.46 g/mol) gives 0.696 moles. 30 g water (molar mass = 18.02 g/mol) gives 1.665 moles. Mole fraction = moles HClO4 / (moles HClO4 + moles water) = 0.696 / (0.696 + 1.665) = 0.295.

Commercial Perchloric Acid Is 70