How to Calculate the Percent by Mass of Nitric Acid in a Mixture?

What is the percent by mass of nitric acid in the mixture?

An 8.89 g sample of an aqueous solution of nitric acid contains an unknown amount of the acid. If 27.1 mL of 0.581 M potassium hydroxide is 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 11.1%

When determining the percent by mass of nitric acid in a mixture, it is important to follow a step-by-step calculation process. Here is how you can calculate it:

Step 1: Data Given

Mass of HNO3: 8.89 grams
Volume of KOH: 27.1 mL = 0.0271 L
Molarity of KOH: 0.581 M

Step 2: The Balanced Equation

HNO3 + KOH → KNO3 + H2O

Step 3: Calculate the Moles of KOH

Moles of KOH = Molarity KOH * Volume
Moles KOH = 0.581 M * 0.0271 L
Moles KOH = 0.0157 moles

Step 4: Calculate Moles of HNO3

For 1 mol of KOH, we need 1 mol of HNO3
For 0.0157 moles of KOH, we need 0.0157 moles of HNO3

Step 5: Calculate Mass of HNO3

Mass KOH = Moles KOH * Molar Mass KOH
Mass KOH = 0.0157 moles * 63.01 g/mol
Mass KOH = 0.989 grams

Step 6: Calculate Mass % HNO3 in Sample

Mass % = (0.989 grams / 8.89 grams) * 100%
Mass % = 11.1%

Therefore, the percent by mass of nitric acid in the mixture is 11.1%.