Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF.The K_a for HF is 3.5 × 10^-4. A)2.86 B)9.31 C)10.54 D)3.46 E)4.69

Question

Quizplus · Accepted Answer

To calculate the pH of the buffer, we need to use the Henderson-Hasselbalch equation, which is pH = pKa + log ([A-]/[HA]).
From the given information, pKa of HF is 3.5 × 10-4.
To find out [A-] and [HA], we use the molarities of the buffer components:

[A-] = 0.058 M LiF
[HA] = 0.058 M HF

Now we can plug in these values into the Henderson-Hasselbalch equation:

pH = 3.5 × 10-4 + log (0.058/0.058) = 3.5 × 10-4 + log(1) = 3.5 × 10-4 + 0 = 3.46

Therefore, the answer is D) 3.46.

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