how do I find the pH of a buffer solution given that 0.010M NH3 mixed with 0.0030M NH4Cl.
Also... a 0.010M HF solution is mixed with 0.030M KF. FIND THE pH of this mixed solution.
Those are done with the Henderson-Hasselbalch equation.
To find the pH of a buffer solution, you'll need to use the Henderson-Hasselbalch equation, which relates the pH of a buffer solution to the pKa (acid dissociation constant) and the concentrations of the acid and its conjugate base.
1. For the first question, you have a mixture of 0.010M NH3 (weak base) with 0.0030M NH4Cl (conjugate acid). The first step is to determine the pKa of the acid.
- The pKa of NH4+ (ammonium ion) can be found in a reference table or calculated using the equation pKa = -log10(Ka). For NH4+, Ka is the equilibrium constant for the dissociation reaction NH4+ ⇌ NH3 + H+.
- Once you know the pKa, you can use the Henderson-Hasselbalch equation: pH = pKa + log10([base]/[acid]).
- Plug in the values: pH = pKa + log10(0.010/0.0030).
2. For the second question, you have a mixture of 0.010M HF (weak acid) with 0.030M KF (conjugate base). The steps are similar.
- Find the pKa of HF (hydrofluoric acid) from a reference table or calculation.
- Use the Henderson-Hasselbalch equation: pH = pKa + log10([base]/[acid]).
- Plug in the values: pH = pKa + log10(0.030/0.010).
Note: The pKa value is necessary to calculate the pH of the buffer solution accurately. It reflects the strength of the acid or base and determines the pH range over which the buffer will effectively resist changes.