Final answer:
The pH of the ammonia buffer solution is approximately 9.183.
Step-by-step explanation:
The pH of an ammonia buffer solution can be calculated using the Henderson-Hasselbalch equation. The equation is pH = pKa + log([NH₃]/[NH₄⁺]). In this case, the pKa value is 9.24, so the pH of the buffer can be found by substituting the concentrations of NH₃ and NH₄⁺ into the equation and calculating the log value of their ratio.
Using the given concentrations of 0.24 M NH₄⁺ and 0.21 M NH₃, we can plug these values into the Henderson-Hasselbalch equation to find:
pH = 9.24 + log(0.21/0.24) = 9.24 + log(0.875) = 9.24 - 0.057 = 9.183
Therefore, the pH of the ammonia buffer solution is approximately 9.183.