20
A . J . JIILLER A S D HERSCHEL HUST
The vapor pressures and boiling temperatures for the ternary mixtures are arranged in table 1. SUJIlIA RI’
The vapor pressures of the system acetic acid-benzene-carbon tetrachloride were obtained by determining the boiling points at three different pressures of fifty-one samples covering the ternary diagram. The boiling points of the system at 1 atmosphere pressure and the vapor pressures a t 60°C. are given. REFERESCE (1) MC~IILLAN, W.R.,
ASD
~~DOSAL H.DJ.: , Ind. Eng. Chem., Anal. Ed. 16, 114 (1943).
HE,1TS O F COhIBCSTIOS. 111‘
THEHEATSOF COMBUSTION OF SOMEPOLYNITROPARAFFINS A. J. MILLER
AND
HERSCHEL HUST
Department of Chemistry, Pztrdzte University, Lafayette, Indaana Received September 18, 1944
The combustion apparatus designed by Miles and Hunt (2) and Crog and Hunt (1) was modified so that a modern Parr oxygen bomb could be employed instead of the glass combustion chamber used with vapors. Essentially, the method is the so-called ‘,ordinary” non-adiabatic calorimetric method, with proper corrections made for heat transfer, the energy involved in the firing of the iron wire, and energy liberated 1)y the formation of nitric acid. Cniform samples of iron 11-ire were used to fire the sample. The energy liberated in firing the iron wire was 19.70 g-cal.150. The heat capacity of the calorimeter n-as determined by using benzoic acid as a standard. It- heat of combustion as furnished by the Sationsl Bureau of Standards is 6315.3 & 1.7 g-cal.leoper gram. Sitric acid formed during the combustion n-as determined by titration n-ith 0.01 A‘ sodium hydroxide. Washburn’s value of 14,621 g-caLl50 per mole was used as the heat of formation of nitric acid under these conditions. The volume of the calorimeter Tvas 358.0 ml., so a sample of approximately 1 g. was used. This sample Tvas made in the form of a pellet and was weighed with an accuracy of 0.05 mg. Five grams of n-ater was placed in the bomb in order to saturate the air with n-ater vapor before the combustion. The initial oxygen pressure in the bomb x i s 30 atmospheres. The nitroparaffins were purified until they gave sharp melting points that did not change on recrystallization. 1 This article is based upon n thesis submitted by A . J. Miller t o the Faculty of Purdue I-niversity in partial fulfillment of the requirements for the degree of Doctor of Philosophy, August, 1943.
21
ALUMISA AND SILICA GELS
The heats of combustion given in the table below were found for the combustion of the solid nitroparaffins to form gaseous carbon dioxide, liquid water, and gaseous nitrogen in a bomb at constant volume and under a pressure of 30 atmospheres at 25°C. NITROPARAFFIN
Dinitroneopent ane.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,3-Dimethyl-2,3-dinitrobutane. ........................ 2-hIethyl-2,3,3-trinitropentane.. ......................... 2-Methyl-2,3,3-trinitrobutane.. . . . . . . . . . . . . . . . . . . . . . . . . . . I 2,2,3,3-Tetranitrobutane.. .............................. ~
. I
~
-746.91 -292.0 -872.40 -700.46 -586.13
& 5.77
f 1.6 i 0.44 f 0.72 i 0.24
REFERESCES (1) CROGA N D HUNT:J. Phys. Chem. 46, 1162 (1942). (2) MILESASD HGNT:J. Phys. Chem. 46, 1346 (1941).
COJIPARISOK OF T H E PROPERTIES O F FRESHLT PRECIPIT.4TED AND HE-ITED ALUAIIXOSILICATES A S D ALUMINA AKD SILICA GELS AND O F CL-41- MINERALS B. DATT.4 Chemical Laboratory, Dacca Cnicersity, I n d i a
S. P. RAYCHAUDHURI
. ~ R DS .
Received October
4, 1944
Raychaudhuri and Qudrat Ghani (13) have found that the uptake of base by pure gels of silica and alumina is comparatively small and that the uptake of base is greatest x-ith aluminosilicate gel having a Si02:-41203ratio of 8.0. They have shown that the buffer curves of the clay minerals do not correspond much in nature to the buffer curves of electrodialyzed precipitated aluminosilicate gels and of the same gels after treatment with hot 10 per cent aluminum chloride solution. Raychaudhuri and Hussain hfiah (14) have shown that freshly prepared aluminosilicate gels possess much less buffer capacity than aged ones, and that the buffer capacity of freshly prepared materials passes through a maximum value with increasing SiO, :M203ratios, whilst with aged ones, the buffer capacity continuously increases as the SiO2:&03 ratios of the precipitates increase, attaining a maximum value with pure silica gel. The maximum value of buffer capacity a t a certain Si02:h1203 ratio of the freshly prepared gels is in agreement with the findings of Mattson (6, 7) and Wiegner (15). The continuous increase in buffer capacity with increase in SiOn:.U2O3 ratio of the aged precipitate proves that aging brings about certain fundamental changes in the structure of the gels, such that the greater the proportion of silicic acid anions in the aged precipitates, the more open is the soil structure, pure
