Note 526 — Chapter XIV · OXIDATION AND REDUCTION REACTIONS. I
Reading edition
According to Wilsmore's tabulation (Z. phys. Chem., 36, 92 (1901)), the potential difference εCu, Cu2+ of copper against a 0.5 molar solution of cupric sulphate, in which [Cu2+] = 0.11, is +0.584 volt. Inserting these values for [Cu2+] and εCu, Cu2+ in the equation εCu, Cu2+ = (0.0575 / 2) log([Cu2+] / K) (see below) and solving the equation for K, we find K = 8E−22. For [Cu2+] = 0.24, εCu, Cu2+ is +0.594 volt and K = 8E−22. In regard to the convention determining the signs used (in the present case εCu, Cu2+ is positive), see the footnote below, p. 262, and in regard to the definition of zero potential, to which the potential differences used in this book refer, see the table and summary at the end of Chapter XV.