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UF~ value of Table 26 (if the UF+ value is accepted) and sl-aowed that the
difference between UF3 and UP, standard free energies in LiF-BeF2-ThFG
(72-16-12 mole X> is virtually identical to that of Table 26,
*
Balnberger et a1.27 have shown that ~3 for pup3 in moltera E ~ ~ B ~ F Q
is -1358 t 10.9 kJ/moPe (-325.4 2 2.6 kcal/rnole) and -1357 P 10.9 kJ/mole
(--324,6 2 2.6 k~d/rasle) at 888 and 988 K, respectively. From these data
a d from the sol~kility of PuF3, they have estimated for pure crystalline
PuF3 the following values:
-
AGf = -1392 t 10.9 kJ/mole (-333.l 2 2.6 kcal/rnole) at 988 K
combining these values with those of Dawaon et a1.28 for the reaction
yields the expression
for crystalline BuPk
NO definitive study sf AG~ for PUF~ in molten f~uoride solution has
been made. Its solubility (by analogy with those of ZrF4,, UFh, and ThP4)
is relatively high.
Also, using the hypothetical standard state of unit
mole fraction, it is more stable [perhaps by 63 kJ/moIe (15 kcal/aaole)]
in solution than as the crystalline solid. If 80, the reaction
*
The standard state of PUP
used for solutes in Table 26,
3(d)
is the hypothetical unit mole fraction