The determination of Gibbs energy of the exchange reaction of sulphides using beta-alumina solid electrolyte

EMF measurements of the cell Na (l) |-alumina | Na₂S + A9₂S + Ag were carried out in the temperature range of 463.4 to 843.7 K. The results were represented by the equationE/V (±0.00057) = 1.75793(±0.00086) – 4.452(±0.014) × 10^–4(T) where 463.4 < T < 737.7 K. The Gibbs energy of the exchange reaction 1/2Ag₂S(s) + Na(l) 1/2Na₂S(s) + Ag(s) was determined from the EMFs. The standard Gibbs energy of formation of Na₂S in the reaction 2Na(l) + 1/2S₂(g) = Na₂S(s) was obtained from the values of EMF and in the literature as (J mol^–1 ± 1160) = –427940 + 124.92T where 463.4 < T < 737.7 K. The eutectic temperature of the Ag₂S-Na₂S system was estimated to be 738 ± 5 K.