The effect of heat transfer on the electrolytic dissolution of Cu in H 3Po 4

Abstract

The rate of dissolution of Cu into 50 %H 3PO 4 when held at an anodic potential of + 1700mV has been studied in the range 20–65°C in the absence of heat flux and in the presence of either positive or negative heat fluxes up to 1·80 cal.cm −2s −1. The effects of such heat fluxes across the specimen surface were investigated by recording the limiting c.ds at constant solution velocity. The limiting c.d., i lim was found to be proportional to the surface/bulk concentration difference, the diffusivity D, and the kinematic viscosity ν, such that i lim= 4·33 × 10 5 . (C s − C b) D 2/3 . ν −1/6. No correction for an applied heat flux was found necessary provided values at the interfacial temperature and not the bulk temperature were used. It was concluded that heat flux alters the mass transfer rate of a diffusion controlled reaction mainly because it alters the surface/solution interface temperature.