Electromotive force study of molten lithium fluoride ... - ACS Publications

AN EMFSTUDY OF MOLTEN LiF-BeF2 SOLUTIONS 201

VoZ. 8, No. 2, February 1969

CONTRIBUTION FROM THE REACTOR CHEMISTRY DIVISION, OAKRIDGENATIONAL LABORATORY, OAKRIDGE,TENNESSEE 37830

A n Electromotive Force Study of Molten Lithium Fluoride-Beryllium Fluoride So1utions1~2 BY B. F. HITCH

AND

C. F. BAES,

JR.

Received July 29, 1968 The potential of the cell BeOlBeFZ, LiFIHF, Hz, Pt was measured over a composition range of 0.30-0.90 mol fraction of BeFz and a temperature range of 500-900’. cell potential was related to the activity of BeFz in the solutions by

E

=

E”

- liTh 2F

Since the

(PH%aBsF8/PHFa)

activity coefficients could be derived for BeFz (and by a Gibbs-Duhem integration for LiF). Usefully accurate measure~ from ments could not be made with pure BeFz in the cell; hence values of E” were calculated using values for U B ~ Fderived the phase diagram and a previously reported heat of fusion (1.13 kcal/mol) giving E’ = 2.4430 - 0.0007952T V. This comparison of the emf data with the LiF-BeF2 phase diagram also indicated that the heat of fusion for BeFz is