Conductivity measurements of dilute aqueous LiOH, NaOH, and KOH solutions to high temperatures and pressures using a flow-through cell

The limiting molar conductance (Lambda (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 degreesC 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 Lambda (0) values of all three hydroxides at densities (rho) greater than or equal to 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.