Question

You have solutions of 0.200 M HNO₂ and 0.200 M KNO₂ (K_a for HNO₂ = 4.00 × 10^–4). A buffer of pH 3.000 is needed. What volumes of HNO₂ and KNO₂ are required to make 1 liter of a buffered solution?

A) 500 mL of each

B) 286 mL HNO₂; 714 mL KNO₂

C) 413 mL HNO₂; 587 mL KNO₂

D) 714 mL HNO₂; 286 mL KNO₂

E) 587 mL HNO₂; 413 mL KNO₂