Calculate the pH of a solution that is 0.210 mol L^-1 in nitrous acid (HNO₂)and 0.290 mol L^-1 in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4. A)3.487 B)3.210 C)13.86 D)10.51 E)4.562

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Quizplus · Accepted Answer

The solution is a buffer, and the pH can be calculated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]). Here, pKa = -log(4.50 × 10^-4) = 3.35, [A-] = 0.290, and [HA] = 0.210. Substituting these values gives pH = 3.35 + log(0.290/0.210) = 3.487.

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