The Percent by Mass of Nitric Acid in Aqueous Solution
What is the percent by mass of nitric acid in the mixture?
A 13.5 g sample of an aqueous solution of nitric acid contains an unknown amount of the acid. If 23.5 mL of 0.434 M barium hydroxide are required to neutralize the nitric acid, what is the percent by mass of nitric acid in the mixture?
Answer:
The percent by mass of nitric acid in the mixture is 3.36%.
Nitric acid is a colorless, fuming, and distinctly corrosive liquid that is a common laboratory reagent and an important industrial chemical. It is used in the manufacture of fertilizers and explosives.
In order to calculate the percent by mass of nitric acid in the mixture, we follow the steps provided in the problem statement:
Calculation:
1. Moles of Ba(OH)2 present = Molarity of base * Volume of base
= 0.434 M * 23.5 mL
= 3.5724 millimoles
2. Moles of HNO3 neutralized = 2 * Moles of Ba(OH)2 used
= 2 * 3.5724 millimoles
= 7.1448 x 10^-3 moles
3. Mass of HNO3 present = Molar mass of HNO3 * Moles of HNO3
= 63.01 g/mol * 7.1448 x 10^-3 moles
= 0.4502 g
4. Percent by mass = (Mass of HNO3 / Mass of sample) * 100
= (0.4502 g / 13.5 g) * 100
= 3.36%
Therefore, the percent by mass of nitric acid in the mixture is 3.36%.