Mean molal activity coefficients and water activities of aqueous rare earth chlorides at 20.0 °C

Abstract

The mean molal activity coefficients and water activities of seven chlorides of the lanthanide elements, including lanthanum, neodymium, samarium, gadolinium, dysprosium, erbium and ytterbium, in aqueous solutions were determined from dilute to saturated concentrations at 20.0 °C. The results were compared with those reported at 25.0 °C. The mean molar activity coefficients of the lanthanide chlorides at 20.0 °C were appreciably larger than those at 25.0 °C, whereas those of potassium and calcium chlorides, which have been used as the references, did not exhibit appreciable differences between the two temperatures. The current work has been intended to investigate the variations of the activity data at varied temperatures; the previous measurements have been done only at 25.0 °C.