A8.20 g sample of an aqueous solution of perchloric acid contains an unknown amount of the acid. if 20.4 ml of 0.922 m potassium hydroxide are required to neutralize the perchloric acid, what is the percent by mass of perchloric acid in the mixture?

The percent by mass of perchloric acid in the mixture is 22.92 %.

Explanation:

We are given:

Volume of potassium hydroxide = 20.4mL = 0.0204 L   (Conversion factor: 1 L = 1000 mL)

Molarity of the solution = 0.922 moles/ L

Putting values in above equation, we get:

By Stoichiometry of the reaction:

1 mole of potassium hydroxide reacts with 1 mole of perchloric acid.

So, 0.0188 moles of potassium hydroxide will react with = of perchloric acid.

Moles of perchloric acid = 0.0188 moles

Molar mass of perchloric acid = 100.46 g/mol

Putting values in above equation, we get:

We are given:

Mass of perchloric acid = 1.88 g

Mass of solution = 8.20 g

Putting values in above equation, we get:

Hence, the percent by mass of perchloric acid in the mixture is 22.92 %.