HEATS OF FORMATION OF THE FLUOBORATES OF LITHIUM, SODIUM AND POTASSIUM.
FULMER RESEARCH INST LTD STOKE POGES (ENGLAND)
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Heats of formation of LiBF4c and NaBF4c from the constituent fluorides, solid alkali fluoride and boron trifluoride gas, at 110C were measured directly. The heat of formation of KBF4c from the constituent fluorides at 25C, based on that of NaBF4c, was determined by comparing the heats of solution in hydrofluoric acid of the pair, NaBF4c KFc, with that of the pair KBF4c NaFc. The following values were obtained -21.40 plus or minus 0.09 kcalmole for LiBF4 -32.04 plus or minus 0.12 kcalmole for NaBF4 -43.13 plus or minus 0.22 kcalmole for KBF4. With the known values of the heats of formation of BF3gas, LiFc, NaFc and KFc, one arrives at the heats of formation of the fluoborates -439.4 plus or minus 0.7 kcalmole for LiBF4 -440.6 plus or minus 0.5 kcalmole for NaBF4 -450.2 plus or minus 0.5 kcalmole for KBF4.
- Physical Chemistry