Question

Calculate the pH of a buffer solution made by combining equal volumes of 0.1 M acetic acid and 0.1 M sodium acetate. The dissociation constant of acetic acid is 1.8 × 10^-5.

Answer 1

To calculate the pH of the buffer solution, we can use the Henderson-Hasselbalch equation:pH = pKa + log [A-]/[HA] First, we need to find the pKa value, which is the negative logarithm of the dissociation constant  Ka :pKa = -log Ka  = -log 1.8  10^-5   4.74Since we are combining equal volumes of 0.1 M acetic acid  HA  and 0.1 M sodium acetate  A- , their concentrations will remain the same in the buffer solution:[HA] = 0.1 M[A-] = 0.1 MNow, we can plug these values into the Henderson-Hasselbalch equation:pH = 4.74 + log 0.1/0.1 Since the ratio of [A-] to [HA] is 1, the log term becomes 0:pH = 4.74 + 0So, the pH of the buffer solution is:pH = 4.74