Features of Lux Acid-Base Reactions in Molten Ionic Solvent Nacl at 830 °C

Some Lux-Flood acid-base reactions (PO neutralisation, MgO and CaO dissolution and CO dissociation) in molten NaCl at 830 °C were studied by potentiometric technique using Pt(O)|YSZ electrode as oxide ion detector. Carbonate ions are found to be a strong Lux-Flood base (pK=2.67±0.2), the value of its dissociation constant is higher than that in molten KCl (pK=3.2±0.2) since thermal stability of NaCO is lower in comparison with KCO. Solubility products (pP=-log P mol-kg) of MgO (pP=8.75±0.06) and CaO (pP=3.77±0.05) and the constant of oxide ion addition to PO (pK=-5.74±0.15) were found. Comparison of the obtained data with the corresponding parameters obtained in the KCl-NaCl equimolar mixture at 700 °C shows that the acidic properties of the participants of heterogeneous reactions weaken with the temperature whereas acidity of anion acids strengthens.