A galvanic cell is based on the following half reactions: Fe2+ + 2e Fe(s) o =

Question:

A galvanic cell is based on the following half reactions:
Fe2+ + 2e– → Fe(s) ϐo = 20.440 V
2H+ + 2e– → H2(g) ϐo = 0.000 V
In this cell the iron compartment contains an iron electrode and [Fe2+] = 1.00 × 10–3 M, and the hydrogen compartment contains a platinum electrode, PH2 = 1.00 atm and a weak acid HA at an initial concentration of 1.00 M. If the observed cell potential is 0.333 V at 25oC, calculate the Ka value for the weak acid HA at 25oC.