What will be the pH of a buffer solution prepared from 0.20 mol NH3, 0.40 mol NH4NO3, and just enough water to give 1.00 L of solution

Question

What will be the pH of a buffer solution prepared from 0.20 mol NH3, 0.40 mol NH4NO3, and just enough water to give 1.00 L of solution

Answer 1

Hey there, we need to use the Henderson-Hasselbach equation for bases:

pOH = pKb + log (B-H⁺/B)

In this case, the B-H⁺ is the protonated base (NH4+) and the Base (B) is NH3. We can look up the pKb of NH3 (4.75).

pOH = 4.75 + log (0.4/0.2) = 5.05

pH = 14 - pOH = 14 - 5.05 = 8.95