Calculate the pH of a buffer that is 0.060 M HF and 0.030 M KF.The K_a for HF is 3.5 × 10^-4. A) 2.06 B) 4.86 C) 3.16 D) 3.56 E) 3.76

Question

Quizplus · Accepted Answer

First, we need to calculate the pKa of HF using the given Ka:

Ka = 3.5 × 10^-4
pKa = -log(Ka) = -log(3.5 × 10^-4) = 3.46

Next, we can use the Henderson-Hasselbalch equation to calculate the pH of the buffer:

pH = pKa + log([A^-]/[HA])

[A^-] = 0.030 M (concentration of KF)
[HA] = 0.060 M (concentration of HF)

pH = 3.46 + log(0.030/0.060)
pH = 3.46 - 0.30
pH = 3.16

Therefore, the correct answer is C.

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