Conductivity Measurements of Dilute Aqueous LiOH, NaOH, and KOH Solutions to High Temperatures and Pressures Using a Flow-Through Cell

Abstract

The limiting molar conductance (Λ0) and molal ion association constant (KA(m)) of dilute (10-5 to 10-3 mol kg-1) aqueous LiOH, NaOH, and KOH solutions were determined by a flow-through conductance cell from 50 to 410 °C and pressures up to 33 MPa. The flow-through cell is designed to measure molar conductances of dilute aqueous electrolytes with a high degree of accuracy at high temperatures and pressures. The results are complementary to our previously reported results measured with a static high-pressure cell, which was incapable of yielding reliable measurements at concentrations < 0.001 mol·kg-1 and densities < 0.4 g·cm-3. The new Λ0 values of all three hydroxides at densities (ρ) ≥ 0.5 g·cm-3 are in good agreement with those measured using the static cell. However, at densities below 0.5 g·cm-3 the new results are slightly higher and less scattered than the previous results at comparable conditions. On the other hand, the KA(m) values of all three hydroxides are in excellent agreement with the static cell results under analogous conditions.