Question

Calculate the pH of the buffer solution containing 0.5 mol NaF and 0.015 mol HF per litre. [pKa = 3.1427].

Answer 1

NaF + HF = Acidic buffer

Given: [NaF] = 0 .05 mol, [HF] = 0 .015 mol

pK_a = 3.1427

PH = PK_a + log₁₀ `(["salt"])/(["acid"])`

∴ PH = 3.1427 + log₁₀ `([0.05])/([0.015])`

= 3.1427 + log₁₀ 3.33

= 3.1427 + 0.5224

= 3.67