A SIMPLE METHOD FOR VAPOR DENSITY DETERMINATIONS PART XI.'-THE DEHYDRATION OF COPPER-SULPHATE PENTAHYDRATE B Y PHILIP BLACKMAN
The bulbs were heated in a thermostat, wax being the heating medium, but no protective outer jacket was employed. The results of the experiments here detailed would seem to show that the evolution of water from the CuS0,.5H20 was a function of the temperature and pressure and does not take place in the evolution of only whole molecules, and consequently the dehydration is comparable to the removal of water from an ordinary aqueous solution of a substance, or to the decomposition by heat of other molecular compounds such as acetaldehyde, ammonia, phosphorus, pentachloride, ammonium chloride, chloral hydrate, etc. The weight of water w given off a t any temperature is calculated from the formula
(where d = the vapor density of water = g ) , and the corresponding internal pressure (atmospheres) 7c of the bulb from the formula
The molecular weight of CuS0,.5H,O = x = 249.66; the molecular weight of 5H,O = y = 90; hence the proportion of water in weight c of copper sulphate = c y / % ; therefore the proportion, h, of water evolved from the hydrate = xw/cy, and consequently the corresponding number of molecules is 5 h. Continued from the Journal of Physical Chemistry, 13, 431 (1909); Chemical News, 100, 174 (1909);Zeitschrift fur physikalische Chemie, 65, 552 (1909).
Philip Blackman
872
EXPERIMENT I c = 0.0582 gram; I, = 194 m m ; Lc = 212 mm; t, = 1 0 . 5 ~ C; V = 22.4 cc
p
=
I
i
I I
1
765 mm;
105
0.0032 0.0037 0.0055 0.0074 0.0089
I IO
0.0101
1.39 1.45 I .60 1.77 I .91 2.03
2
W
IC
k
5h
176 171 I59
0.0036 0.0043 0.0062 0.0076
I . IO
0.22
1.1
1.44 1.53 I .64 I .80 1.88
0.26 0.38
1.3
0 .5 0
2.5 3.1 3.4
85 90
95 IO0
4
1
85 90
95 IO0
105 IIO
t* 90
95 IO0
105 IIO
115
~
i
:;
135
1
I
I
169
157 144 I39 I35 I33 131
0.0100 0.0110
w
0.004168 0.004466 0.00607 0.00849 0.00954 0.01043 0.01090 0.01 138
,
l .31 1.35 I .46 I .61 I .69 1.77 I .82 I .87 I
J
0.15 0.18 0.26 0.35 0.43 0.48
1.9
0.62 0.68
A
5h
0.28 0.29 0.40 0.56 0.63 0.69
1.3 1.4 2 .o 2.8
0.72
0.75
I
3.1 3.4 3.6 3.7
Simple Method f o r Vapor Density Determinations
873
EXPERIMENT IV c = 0.0613 gram; I,
fi
,
1,
~
85 90 95 IO0
~
10.5 I IO
~
I
= =
192 mm; I,, 767 mm; V =
l
= 211 20.5 cc
w
I26
=
1 3 . 5 ~C ;
It
0.00261 I53 145
m m ; f,
0.00280
1.33 1.37
0.00430 0.00553 0.00665 0.00874 0.00985
1.63 1..74 1.94 , 2.056 i
I
.SI
0.I 2
1
0.59 0.63 0.97 I .25
0.13 0.19 0.25 0.30
I .5
0
1.97
0.44
2.22
2.50
c
=
0.1034 gram;
L = 244 t,
=
m m ; Lc = 262 mm; 12.5C ~ ; V = 40.5 cc
p
h
IO0 I IO
I77
140
I35 130
0.0064 0.0097 0.0138 0.0202
I
I
1.44 1.61 ; : . I
0.0272
0.0293
2.69
=
755 mm;
5h
0.13
0.6
0 . I8
0.9
0.26 0.37 0.54 0.72 0.78
1.3 I .8 2,7 3.6 3.9
