A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate. Use 1.80 × 10−5 as Ka for acetic acid

Question

A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate. Use 1.80 × 10−5 as Ka for acetic acid

Answer 1

You didn't actually pose a question, but I'll assume you are looking for the final pH of this buffer solution.

Since the volume of the acid (HA) and the conjugate base (Ac-) are equal, the final concentrations of each will be halved. Thus, final [HA] = 0.100 M and [A-] = 0.300 M. Using the Henderson Hasselbalch equation to determine the pH of this buffer, we have...

pH = pKa + log [A-][HA] and the pKa = -log Ka = -log 1.80x10-5 = 4.74 = pKa

pH = 4.74 + log (0.300/0.100) = 4.74 + log 3

pH = 4.74 + 0.477

pH = 5.22