The Standard Potential of the Two‐Phase Cu Amalgam and Other Cu Electrodes and Calculation of CuSO4Activities in Aqueous Solutions

Abstract

AbstractThe potential difference between two‐phase copper amalgam electrodes and pure, solid copper electrodes (single crystals of various orientations, strained and unstrained polycrystalline sheet) was measured in the range 15 to 26°C. At 25°C the two‐phase amalgam was 4.78 mV more positive than the solid electrodes which all gave identical results. From the potential difference and its temperature coefficient, μ0andS0of the intermetallic compound CuHg, were calculated. A discussion on previous determinations of copper standard potentials, the activity of CuSO4in solution, and the standard potential of the Hg, Hg2SO4|SO42‐electrode is included. The following purely empirical relationship is proposed between mean activity coefficient γ and concentrationm0of CuSO4solutions in the range 3 · 10−2<m0< 3 · 10−1mol kg−1: γ = 0.0502m0−1/2.