Maximum Work

[ayushibanerjee06]

For maximum work calculations, why is Q = anode/cathode when the anode is the reactants and cathode is the products?

[VPatankar_2L]

For maximum work calculations, the anode is in the reactants while the cathode is in the products. For example with question 6N.3 part a, Pt(s)|H2(g, 1.0 bar)|HCl(aq, 0.075 mol/L)||HCl(aq, 1.0 mol/L)|H2(g, 1.0 bar)|Pt(s), the oxidation reaction is H2 --> 2H+ + 2e- while the reduction reaction is 2H+ +2e- --> H2. the net reaction will be 2H+ + H2 --> H2 + 2H+ where the 2H+ on the products side is the 2H+ from the products part of the oxidation reactiion (0.075 M) and the 2H+ on the reactants side comes from the reactants side of the reduction reaction (1M).

As a result, Q = [products]/[reactants] = [H+]^2/[H+]^2 = [0.075]^2/[1]^2.