What is the pH of a buffer system that contains 0.18M NH4+ and 0.14M NH3? The pKa of NH4+ is 9.25.
Use the Henderson-Hasselbalch equation.
2.0*10M
pH=pKa+log(base/acid)
pH= 9.25+log(0.14/0.18)
pH= 9.14
To determine the pH of a buffer system, we need to use the Henderson-Hasselbalch equation, which is pH = pKa + log([A-]/[HA]).
In this case, NH3 acts as the base (A-) and NH4+ acts as the acid (HA). The pKa of NH4+ is given as 9.25.
First, we need to calculate the ratio of [A-]/[HA].
[A-]/[HA] = 0.14M NH3 / 0.18M NH4+
= 0.7778
Now, substitute the values into the Henderson-Hasselbalch equation:
pH = 9.25 + log(0.7778)
≈ 9.25 - 0.109
≈ 9.14
Therefore, the pH of the buffer system is approximately 9.14.