HEATCONTENT AND ENTROPY OF La203, Pr6011 AND Ndz03
Nov., 1951
5099
TABLE I Run
B
C
12.0 f 0 . 2 21 f 2 198 f 2
76.0 f 0 . 5 20-215 123-213 0-162 521 f 8 86 4 84 i 4
A
Duration, hr. Temp. range, OC. Hydrogen chloride partial pressure, mm. Aluminum chloride partial pressure, mm. counts Initial specific activ. of HCI gas Final specific activ. of HC1 gas min. mole Decrease in sp. activ. of HCI gas, %
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plete exchange. This fact points to the possible existence of HAlCl4 but it does not prove its existence, since there are other conceivable paths for exchange. Taken as a whole, the findings of this research present the following picture in regard to compound-formation in the system studied. At lower temperatures there is absolutely no evidence of chemical reaction. This follows from the absence of pressure plateaus concerning phase equilibria measurements and no decrease in specific activity of the gas during exchange runs a t room temperature. But a t higher temperatures, creating the all-vapor system and allowing for a slight dissocia-
1.0 f 0 . 2
25 f 2 87 f 1 0
0
508 f 15 500 f 15
