Final answer:
To determine the pH and pOH of a buffer solution containing boric acid and sodium borate, you can use the Henderson-Hasselbalch equation. The pH is 9.2270 and the pOH is 1.1066.
Step-by-step explanation:
The pH and pOH of a buffer solution can be determined using the Henderson-Hasselbalch equation. The Henderson-Hasselbalch equation is:
pH = pKa + log([A-]/[HA])
First, we need to calculate the concentrations of the conjugate acid and base. Given that the volume of the solution is 0.25 L, we can use the given molarities and convert them to concentrations:
[B(OH)3] = 0.0196 M / 0.25 L = 0.0784 M
[NaB(OH)4] = 0.0331 M / 0.25 L = 0.1324 M
The ratio of the conjugate base ([NaB(OH)4]) to the conjugate acid ([B(OH)3]) is therefore:
[NaB(OH)4] / [B(OH)3] = 0.1324 M / 0.0784 M = 1.6875
Next, we can calculate the pOH by taking the negative logarithm of the hydroxide ion concentration, which is equal to the concentration of the conjugate acid:
pOH = -log([B(OH)3]) = -log(0.0784) = 1.1066
Finally, we can calculate the pH using the Henderson-Hasselbalch equation:
pH = 9 + log(1.6875) = 9.2270