The K_a of hydrazoic acid (HN₃)is 1.9 × 10^-⁵ at 25.0 °C. What is the pH of a 0.15 M aqueous solution of HN₃?

Question

Quizplus · Accepted Answer

To find the pH, we first set up the expression for the dissociation of HN3: HN3 ⇌ H+ + N3-. Using the Ka value, we set up the equation: Ka = [H+][N3-]/[HN3]. Assuming x is the concentration of H+ ions, we have Ka = x^2/(0.15-x) ≈ x^2/0.15. Solving for x gives x ≈ 1.7 × 10^-3. The pH is -log(1.7 × 10^-3) ≈ 2.77.

The Ka of Hydrazoic Acid (HN3)is 1

The K_a of Hydrazoic Acid (HN₃)is 1