The system NH4NO3NaNO3Pb(NO3)2H2O

Abstract

AbstractAs an extension of the investigations previously published on the vapour pressures of aqueous solutions saturated with one or two of the salts NH4NO3, NaNO3 and Pb(NO3)2, the vapour pressure of the five phase equilibrium solid NH4NO3solid NaNO3solid Pb(NO3)2saturated solution‐water vapour has now been determined from 10° C to the end‐point of this line. This end‐point is the eutectic in the ternary system NH4NO3NaNO3Pb(NO3)2. We have determined this ternary eutectic. It was found to be situated at a temperature of 112.3 ± 0.1° C and a composition 62.7 per cent by weight of NH4NO3, 15.6 per cent NaNO3 and 21.7 per cent Pb(NO3)2.The transition point γ → δ‐NH4NO3 causes a slight change in the slope in the vapour pressure curve at 84.2° C. The maximum occurring in the vapour pressure curve is situated at 85.9° C, thus at a temperature at which δ‐NH4NO3 is stable.The relative vapour pressure, plotted as a function of the temperature, is seen for the system now investigated to be again represented by two almost straight lines, one valid for the temperatures below 84.2° C where γ‐NH4NO3 is stable and the other for the range 84.2°‐112.3° C where δ‐NH4NO3 is stable.The formula previously published for the calculation of maxima in vapour pressure lines of saturated salt solutions, appears in this case also to give a value which agrees well with the experimentally determined one.