Densities and Molar Volumes of Molten Alkali Carbonate Binary Mixtures

Density and molar volumes were determined for the molten lithium, sodium, and potassium carbonate binary mixtures over the complete composition range. Molar volumes of the sodium‐potassium carbonate binary exhibit ideal behavior but the lithium binaries show positive deviations in the 0.25 to 0.67% mole lithium carbonate region. An attempt is made to handle the results using thermodynamic reasoning. It is possible to give a detailed explanation of the observed behavior by postulating that inbalances in repulsive cation interactions, caused by the relatively small size of the lithium ion, forces changes in anion‐cation bonding in the melt micro‐structures.