PROPERTIES OF PVRG HYDROGET\' PE;KOXIDE. Physical constant.
Hydrogen peroxide.
Freezing point.. . . . . . . . . . . . . . . . . . . . . . . --I .70° Density of liquid a t 0 ' . . . . . . . . . . . . . . . . I ,4633 Mean coefficient of expansion -10' to +zoo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . o.ooro7 Density of soiid.. . . . . . . . . . . . . . . . . . . . . . I ,614 Specific heat of liquid. . . . . . . . . . . . . . . . . o .579 Latent heat of fusion.. . . . . . . . . . . . . . . . . 74 calories Specific heat of solid, . . . . . . . . . . . . . . . . . . 0.470 Slirface tension 0 ' . . . . . . . . . . . . . . . . . . . . 7 8 . 7 dynes Association (Ramsay and Young) a t o '. , . 3.48 Viscosity 0 ' . . . . . . . . . . . . . . . . . . . . . . . . . . o ,01829 Refractive index (D) 2 2 '. . . . . . . . . . . . . . I ,4139 Molecular refractive power (D). . . . . . . . 5 , g o
2569
11% Water. O0
0.99987 0.00000
0.9167 z
.o
80 calories 0.472 7 5 .5 dynes .3 .5t: 0,01778 I
3330
3.715
MONTRZAL, CANADA.
[CO~TRIEUTION FROM THE CI-ISMISTRY DEPARTMGKT OF NLCGILLUNIVERSITY 1
E FROPEWTIES OF PURE HYDROGEN F
E
~
111 O.
E u 0 MAASSAND 0 . W. I-IERZBSKG Received September 25, 1920.
This second paper deals solely with the freezing-point curve of solutions of hydrogen peroxide ar*d water. These solutions were prepared by concentrating 3% hydrogen peroxide and puri€ying the resultant concentrated solution by means of a distillation. As the only volatile impurity contained by the original solution consisted of a trace of hydrochloric acid, the final product may be looked upon as having Seen pure except for a trace of this acid ~7hichfound its way into the distillate. In this way an 867, solution was obtained. In order to obtain the freezing points of hydrogen peroxide-water mixtures a weighed amount of this 86% peroxide solution was placed in a test-tube. A platinum thermometer, reading to 0.1 was immersed in it. The tenperature was lowered by means of a suitable freezing mixture until crystals formed. All but a few of these were allowed t o melt and then the temperature was slightly lowered until crystallization again set in, the liquid in the meantime being qigorously stirred. The solution was then allowed to warm up slowly, the freezing point being taken as the teniperature a t which the last crystals melted under vigorous stirring. The solution was analyzed; an adequate amount of water, sufficient t o dilute the solution a few per cent. was added, and then the whole procedure repeated. I n this way the freezing points a t various concentraPions were determined. The solutions between the concentrations 4 0 % and 60% hydrogen peroxide had a tendency to supercool into a thick viscous mass, but when allowed t o stand a t a temperature of --go*' crystallization started after some time. Carbon dioxide ether under
a
vacuum was uyed a i frepLing misturc
111 this
case
~
~
~
0. MAASS AND 0. W. HGRZBERG.
2570 Hydrogen peroxide.
70.
Freezing point of solution.
Hydrogen peroxide,
c.
eo .o
-14
80.4j 74 .o og . 2 67.4 Gj .A 63.05
--22.7
%. 49.8 47 .o 46.21 42.02 37 . g o 36.47
.0
--32 .5 --39 . 0 --4 1 .5
jj .06
--45.5 -50 .o -52 .5 --54. j --jq. I 3 ---53 .6
53.7
-52,
61.14
j 8 .X 56.2
Fig
-50.8 -51.8 -46.25 -38 .O -35.7 -28.5
2 2 .,jO
-17
9.96 4.9
PrRCEN'AGE
c.
-51.7
31.96 27.72
15.91
j
Freezing point of solution.
-23.4.
.o I ,I
- G.I - 3.4
H,O, I
'The graph (Fig. I ) of these results gives a good idea of the variation of the freezing point with concentration. It is seen that a molecular coinpound 2Rz0-HzO2is formed corresponding t o a, compositioii 48.6Tc of hydrogen peroxide. Wolff ensteinl had cooled down concentrated solutions of hydrogen peroxide and analyzed the crystals formed He came to the conclusion that z compounds existed, represented by the formulas--lHz02.H~0 and HzO&IZO. The freezing point curve gives no evidence for the existence 0; the former, and i t is probable that the belief in its existence was due t o the difficulty of separating the solution completely from the hydrogen peroxide cry+ tals a t low temperatures. This phenomenon was considered in the first paper on hydrogen peroxide. Summing up. the freezing point curve of hydrogen peroxide-water ha? been determined, arid one molecular compound, namelv, Hz02.zEXtQ, witil a meltinq point of - j ~O , has been shown t o exist, h!!OnTWAL,
CANADA
Wolffenstein, Bel , 27, 3307 ( 1 8 ~ 4 )
