Thermal Liquid Junction Potentials

The e.m.f. of a thermogalvanic cell is the result of four main effects (a) electrode temperature, (b) thermal liquid junction potential, (c) metallic thermocouple and (d) thermal diffusion gradient or Soret. 

The determination of absolute or ideal energies of activation is handicapped by the fact that the variation of the cell temperature introduces undertainties either at the reference electrode—solution interface, when both working and reference electrodes are at the same temperature, or from the thermal liquid junction potential in a non-isothermal measurement [5,36]. 

Pressure-balanced AglAgCl reference electrodes have been extensively used for corrosion monitoring in boiling water reactor environment [41]. The potential of the thermoelectrochemical cell AglAgCl versus the standard hydrogen electrode at temperature, T, was expressed as a sum of the isothermal potential and thermal liquid-junction potential. 

The cOTisiderations mentioned lead to the following consequence In an electrolyte solution, the existence of a temperature difference must give rise to a voltage across the zraie of temperature profile, the so-called thermal liquid junction potential, Etljp- If the contributions have to be determined, the thermodynamic contribution mentioned above can be made reversible just by measuring cell voltage under open circuit condition , i.e. without current flow. The second contribution, in contrast, is irreversible and not constant with time. 

Table 2.1 Thermal liquid junction potentials in aqueous KCl solution and their temperature coefficients for7-e ,d = 298K[12]...

The quantity E-ru in Eq. (45) is the thermal liquid junction potential, or the thermal diffusion potential, which arises from the coupling between heat flow and mass flow (diffusion) in accord-... 

In 1979, Macdonald et al. successfully measured the initial thermal liquid junction potential of the thermal cell... 

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