The following question refers to a solution that contains 1.59 M hydrofluoric acid,HF (K_a = 7.2 $\times$ 10^-⁴),and 3.00 M hydrocyanic acid,HCN (K_a = 6.2 $\times$ 10^-¹⁰). What is the pH of this mixture of weak acids? A)1.47 B)2.94 C)4.50 D)9.01 E)12.53

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Quizplus · Accepted Answer

The correct answer is A because the pH of the solution can be calculated using the Henderson-Hasselbalch equation, which is pH = pKa + log([A-]/[HA]). For hydrofluoric acid, pKa = 3.14 and [A-]/[HA] = 1.59 M/1.59 M = 1. For hydrocyanic acid, pKa = 9.21 and [A-]/[HA] = 3.00 M/3.00 M = 1. Therefore, the pH of the solution is pH = 3.14 + log(1) = 3.14.

The Following Question Refers to a Solution That Contains 1 ×\times×

The Following Question Refers to a Solution That Contains 1 $\times$