For nitrous acid, HNO₂, K_a = 4.0 * 10^-⁴. Calculate the pH of 0.27 M HNO₂.

Name: For nitrous acid, HNO 2 , K a = 4.0 * 10 - 4 . Calculate the pH of 0.27 M HNO 2 .
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Quizplus · Accepted Answer

To find the pH, we use the formula for weak acid dissociation: HNO2 ⇌ H+ + NO2-. The expression for Ka is [H+][NO2-]/[HNO2]. Assuming x is the concentration of H+ ions, Ka = x^2/(0.27-x) ≈ x^2/0.27. Solving for x gives x = √(Ka * 0.27) = √(4.0 × 10^-4 * 0.27) ≈ 0.0104. The pH is -log(0.0104) ≈ 1.98.

For Nitrous Acid, HNO2, Ka = 4

For Nitrous Acid, HNO₂, K_a = 4