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

The limiting molar conductance (Λ 0 ) and molal ion association constant ( K A (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 Λ 0 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 K A (m) values of all three hydroxides are in excellent agreement with the static cell results under analogous conditions.