Question 12.5: Calculate the molality of a 35.4 percent (by mass) aqueous s...

Calculate the molality of a 35.4 percent (by mass) aqueous solution of phosphoric acid ( $H_{3}PO_{4}$ ). The molar mass of phosphoric acid is 97.99 g.

Strategy In solving this type of problem, it is convenient to assume that we start with 100.0 g of the solution. If the mass of phosphoric acid is 35.4 percent, or 35.4 g, the percent by mass and mass of water must be 100.0% − 35.4% = 64.6% and 64.6 g.

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