Study of the Cu|Cu(NO3)2·H2O|Cu electrochemical thermocouple at low temperatures

Abstract

Abstract The thermoelectric properties of the non-isothermal Cu|Cu(NO 3 ) 2 |Cu cell have been studied. It has been established that the value of the thermoelectromotive force ( E ) changes linearly with temperature up to the freezing point of the solution. At lower temperatures than this, at concentrations where the frozen phase consists of pure ice, E increases due to the increase in the concentration of the solution, whereas at compositions where the frozen phase is Cu(NO 3 ) 2 ·XH 2 O, the decrease in Cu(NO 3 ) 2 concentration results in a decrease of E . At temperatures lower than the freezing temperature, the potential difference measured between the poles of the cell, in addition to the thermo-emf—due to the concentration change during freezing—includes also the electric potential difference caused by the concentration difference between the half-cells. The slope of the E –Δ T straight lines ( E ′) increases with the concentration of cupric nitrate solutions.