BY PHILIP BL.\CliM,\N
PART VI The Dissociation of Phosphorus Pentachloride The method employed was t h a t described by the author,' the heating medium being paraffin wax contained in an oblong sheet-iron trough, but no glass jacket round the bulb (as a protection against p o 4 b l e bursting) was employed. The pentachloride began to disappear, i. e . , to volatilize, a t about 16oo-17o0, the vaporization being complete a t about 180'; some of the substance could be seen previously existing in a liquid condition. The total time occupied in the readings for I and t,^ was about 3 hours. The densities ( d ) as calculated by the author are, a t corresponding temperatures, greater than those determined by Dumas, and this is no doubt due t o the fact that under the considerable internal pressures of the bulb the pentachloride dissociated to a smaller extent than it would have done under normal atmospheric pressures. The formula used for the calculation of the pressures (in atmospheres) is x
+ f 2 ) , / i 6 0 1 ( 2 i 3+ 4 )
=pL(~i3
The readings for 1 a t I S O O , 17.5'~ and 170' were taken while the thermostat was cooling down. -
~
~~
-
Jour. Pliys. Chem.,
12,661
(1908).
+
(ti, = j2.06 = the vapor-de~isit?. of N.J3 C1,; d, = IO+.'' :-the vapor-density of PC1,); 1 0 , 1 4 6 5 gram; V = 34.6 C C ; L = 2 0 2 m m ; L, = 2 1 2 111111; t , ~= 1 8 C~;i) 76o r n t i i LI
~
I 129 128
83.80 82.16 80.jj
185
I27
78.98
190
1-14
74.48
Igj
12;
200
I21
2Oj 210
120
119
70.58 68.95 67.64
21j 220 225
118
66.36
230 235 240
I15
I70 I75
180
245 2jO
I
