Calculate the molarity of a solution made by adding 35.0 mL of concentrated perchloric acid (70.5 % by mass, density 1.67 g/mL) to some water in a volumetric flask, then adding water to the mark to make exactly 2000 mL of solution. (It is important to add concentrated acid or base to water, rather than the other way, to minimize splashing and maximize safety.)

Question

Chemistry

Brenda Ayers

22 December, 04:34

Calculate the molarity of a solution made by adding 35.0 mL of concentrated perchloric acid (70.5 % by mass, density 1.67 g/mL) to some water in a volumetric flask, then adding water to the mark to make exactly 2000 mL of solution. (It is important to add concentrated acid or base to water, rather than the other way, to minimize splashing and maximize safety.)

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Stephanie Ramos · Answer 1

Molarity is equal to the number of moles of solute per liter solution.

number of moles solute: (molar mass of perchloric acid is 100.45 g/mol)

35.0 mL * (1.67 g/mL) * 0.705 * (mol/100.45 g) = 0.41 moles

liter solution = 2000 ml * (1 L/1000 ml) = 2 L

molarity is equal to 0.41 moles / 2 L = 0.205 M