Conductivity measurements of dilute aqueous HCl solutions to high temperatures and pressures using a flow-through cell

The limiting molar conductance Lambda (0) and molal ion association constan t K-A(m) of dilute (10(-5) to 10(-3) mol . kg(-1)) aqueous HCl solutions we re determined using a flow through conductance cell at temperatures from 10 0 to 410 degreesC and densities from 0.96 to 0.27 g.cm(-3). The flow-throug h cell is designed to measure molar conductances of dilute aqueous electrol ytes with a high degree of accuracy at high temperatures and low densities. The resulting Lambda (0) values are in general agreement with those report ed by Noyes (1907), Wright et al. (1961), Pearson et al. (1963), and Lukash ov et al. (1975) for densities that range from 0.7 to 0.3 g.cm(-3) at compa rable conditions. However, when compared to values reported by Frantz and M arshall (1984), the new results are in agreement at densities (rho) > 0.5 g .cm(-3), but from 0.5 to ca. 0.4 g.cm(-3), their calculated results are 5-1 1% higher. Below 0.4 g.cm(-3) where the experimental uncertainties are larg e, the weighted values from the new study are approximately 14-35% lower. W ithin experimental uncertainties, the new K-A(m) values are in good agreeme nt with the reported values from Franck (1956), Wright et al. (1961), Pears on et al. (1963), and Lukashov et al. (1975) at densities from 0.7 to 0.3 g .cm(-3) but are only in fair agreement with the Frantz and Marshall values at densities above 0.5 g.cm(-3). Below 0.5 g.cm(-3), the latter values are 0.5-2.5 log units higher than the new results.