VAPOR-PRESSURE MEASUREMENTS OF CHLORIC ACID AND CHLORIC ACID PLUS SODIUM-CHLORATE AQUEOUS-SOLUTIONS

Chloric acid + sodium chlorate mixtures have been proposed as a substi tute for some of the sodium chlorate and sulfuric acid in the generati on of chlorine dioxide. This paper continues our work on physical prop erty characterization of chloric acid + sodium chlorate solutions. A d ual ebulliometric setup was employed to evaluate the vapor pressure-te mperature relationship of chloric acid and chloric acid + sodium chlor ate solutions. The natural log of vapor pressures for chloric acid sol utions (1.01-3.82) mol L(-1) over the temperature range (35-79) degree s C was a linear function of chloric acid concentration and the recipr ocal of the temperature. Vapor pressures were determined for sodium ch lorate + chloric acid solutions for (0.85-4.25) mol L(-1) sodium chlor ate, (0.73-3.59) mol L(-1) chloric acid, and (35-83) degrees C. All of the data were well correlated by an equation relating the natural log of vapor pressure to sodium chlorate concentration, chloric acid conc entration, and the reciprocal of the temperature. Some solutions with high chlorate ion concentrations at high temperatures developed a yell ow or pink color. Vapor phase measurements showed that the vapor press ures determined in these experiments are due to water with a trace con tribution from another component.