THEORY OF THERMOCELLS - TRANSPORTED ENTROPIES, AND HEAT OF TRANSFER IN SULFATE MIXTURES

The transported entropy of silver ion, S(Ag+)*, and the heat of transfer, q2*, for Ag2SO4, have been calculated from electromotive force (EMF) measurements in the cell Ag(T1) \ Ag2SO4-Li2SO4 \ Ag(T2). Results give S(Ag+)*, = 102 +/- 6 JK-1 mol-1 when 0.1 < x(Ag2SO4). From this we drive S-4(2-) = 220 JK-1 mol in pure silver sulfate and S(Li+) =54 JK-1 mol-1 in lithium-silver sulfate mixtures. For smaller mole fractions of Ag2SO4, S(Ag+)*, increases. The heat of transfer, q2*, is negative and varies with composition. The sign indicates that Ag2SO4 is enriched on the hot side. The Thomson coefficient for molten pure AgSO4 is tau(Ag+) = 30 JK-1 mol-1. From this we derive tau(SO42-) = 140 JK-1 mol-1. Kinetic and thermodynamic models for the transported entropy and heat of transfer are discussed. Some models can be rejected.