Calculate the pH of a solution prepared by mixing 50 mL of a 0.10 M solution of HF with 25 mL of a 0.20 M solution of NaF. pK_a of HF is 3.14. A) 5.83 B) 12.00 C) 3.14 D) 7.35 E) 10.80

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Quizplus · Accepted Answer

The solution is a buffer solution made of HF and its conjugate base F-. Using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of F- and [HA] is the concentration of HF. After mixing, [HF] = (0.10 M * 50 mL) / 75 mL = 0.0667 M and [F-] = (0.20 M * 25 mL) / 75 mL = 0.0667 M. Thus, pH = 3.14 + log(0.0667/0.0667) = 3.14.

Calculate the PH of a Solution Prepared by Mixing 50