The Percent by Mass of Nitric Acid Calculation

How to calculate the percent by mass of nitric acid in a mixture?

Given data: A 9.03 g sample of an aqueous solution of nitric acid, neutralized by 12.0 mL of 0.655 M barium hydroxide.

Calculation and Explanation

When neutralizing an unknown amount of nitric acid with barium hydroxide, the following steps can be followed to determine the percent by mass of nitric acid in the mixture:

1. Calculate moles of barium hydroxide (Ba(OH)2) used in neutralization.
2. Determine the moles of nitric acid (HNO3) that reacted with Ba(OH)2.
3. Calculate the mass of HNO3 based on the moles obtained in step 2.
4. Determine the mass percent of HNO3 in the sample.

Detailed Calculation

Given that the mass of HNO3 in the sample is 9.03 grams, and 12.0 mL of 0.655 M Ba(OH)2 is required to neutralize the nitric acid:

1. Calculate the moles of Ba(OH)2 used:
   • Moles of Ba(OH)2 = Molarity of Ba(OH)2 * Volume of Ba(OH)2
   • Moles of Ba(OH)2 = 0.655 M * 0.012 L = 0.00786 moles
2. Calculate the moles of HNO3 reacted:
   • Since the balanced equation is Ba(OH)2 + HNO3 → Ba(NO3)2 + H2O, 1 mole of Ba(OH)2 reacts with 1 mole of HNO3
   • Moles of HNO3 = 0.00786 moles
3. Calculate the mass of HNO3:
   • Mass of HNO3 = Moles of HNO3 * Molar Mass of HNO3
   • Mass of HNO3 = 0.00786 moles * 63.01 g/mol = 0.495 grams
4. Calculate the mass percent of HNO3 in the sample:
   • Mass Percent = (Mass of HNO3 / Total Sample Mass) * 100%
   • Mass Percent = (0.495 grams / 9.03 grams) * 100% = 5.48%

Therefore, the percent by mass of nitric acid in the mixture is 5.48%.