A buffer solution at pH 10 has a ratio of [HA]/[A−] of 10. What is the pK_a of the acid?

Name: A buffer solution at pH 10 has a ratio of [HA]/[A−] of 10. What is the pK a of the acid?
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Quizplus · Accepted Answer

The Henderson-Hasselbalch equation is used to relate pH, pKa, and the ratio of the concentrations of the acid and its conjugate base: pH = pKa + log([A−]/[HA]). Given pH = 10 and [HA]/[A−] = 10, we have log([A−]/[HA]) = log(1/10) = -1. Therefore, 10 = pKa - 1, which gives pKa = 11.

A Buffer Solution at PH 10 Has a Ratio of [HA]/[A−]