Chemistry Problem Solving with Titration: Determining Nitric Acid Molarity

What is the molarity of the nitric acid solution?

If 21.1 mL of 0.110 M solution of calcium hydroxide are required to neutralize 23.8 mL of the nitric acid, what is the molarity of the nitric acid solution?

Answer:

The molarity of the nitric acid solution is 0.195 mol/L.

To determine the molarity of the nitric acid solution, we need to follow these steps:

(a) Balanced Equation

The balanced equation for the reaction between nitric acid (HNO₃) and calcium hydroxide (Ca(OH)₂) is:
2HNO₃ + Ca(OH)₂ ⟶ Ca(NO₃)₂ + 2H₂O

(b) Moles of Calcium Hydroxide

Given that 21.1 mL of 0.110 M Ca(OH)₂ are used, we can calculate the moles of Ca(OH)₂:
Moles of Ca(OH)₂ = 21.1 mL x 0.110 mmol/mL = 2.321 mmol Ca(OH)₂

(c) Moles of Nitric Acid

Using the balanced equation, we know that the molar ratio between HNO₃ and Ca(OH)₂ is 2:1. Therefore, the moles of HNO₃ can be calculated as:
Moles of HNO₃ = 2.321 mmol Ca(OH)₂ x (2 mmol HNO₃ / 1 mmol Ca(OH)₂) = 4.642 mmol HNO₃

(d) Molarity of Nitric Acid

The molarity (c) of a solution is calculated using the formula c = n/V, where n is the moles of solute and V is the volume of the solution in liters. Therefore,
Molarity of HNO₃ = 4.642 mmol / 23.8 mL = 0.195 mol/L

Thus, the molarity of the nitric acid solution is 0.195 mol/L.