The of a weak acid, , is . The of a weak base, , is . What will be the exact pH of an aqueous soluti — Ionic Equilibrium Chemistry Question
Question
The $pK_a$ of a weak acid, $HA$, is $4.80$. The $pK_b$ of a weak base, $BOH$, is $4.78$. What will be the exact pH of an aqueous solution of the corresponding salt, $BA$, at standard temperature?
Answer: A
💡 Solution & Explanation
The salt $BA$ is formed from a weak acid and a weak base. The formula for the pH of a WA-WB salt solution is independent of concentration: $pH = 7 + \frac{1}{2}(pK_a - pK_b)$. Substituting the given values: $pH = 7 + \frac{1}{2}(4.80 - 4.78) = 7 + \frac{1}{2}(0.02) = 7 + 0.01 = 7.01$.
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