Trouton s constant

The heat of formation of liquid arsenic trifluoride has been obtained 1 indirectly by determining the heats of dissolution of the trifluoride and of a mixture of arsenious oxide and sodium fluoride in about one litre of normal sodium hydroxide solution. The value obtained was 198,300 calories. Assuming Trouton s constant to be 21, the heat of vaporisation is about -7000 calories, so that the heat of formation of gaseous arsenic trifluoride is 191,300 calories. 

Trouton s constant The constant 85 JK 1 mol-1 that occurs in Trouton s rule. 

Liquid bis(pentamethyldisilanyl)amine is considerably associated as compared with bis(trimethylsilyl)amine, as indicated by the respective values of Trouton s constant, 28.1 and 23.5. This is probably due to the increased availability of vacant silicon 3d orbitals at the silicon-silicon bond which might favor an interaction between two molecules (1,188). 

Table 4.1 The structuredness of solvents, measured by their Trouton s constant, the entropy deficit, the dipole orientation correlation coefficient, and the heat capacity density...

Herz, Z. Elektrochem., 1919, 25, 323 1920,27, 26,109. Herz s equation follows from the equation of Prud homme, J. Chim. Phys., 1913, 11, 589, M=AKeQe, Kt=Tjpc (Pc atm.), since A is constant, 21-55 to 21-86, equal to Trouton s constant, MklTi=21, therefore UlTi M/KeQc =PclT,ec. 

The value of the Trouton s constant for OsOFg, 23-4 e.u. is similar to values reported for related compounds, The following values for hexafluorides WF, 21-8, ReFg 22-3. OsFg 210, IrF, 22-6, and PtF, 20-6 e.u., show that OsOFg is not sigi cantly more associated in the liquid phase, than is, for example, IrF,. It is possible that all of these values are equivalent within the experimental error. 

The boiling point (extrapolated) is 87° and the Trouton s constant is 19.6 cal/deg mole. The compound is fairly stable at room temperature when sealed in a Pyrex glass tube and is easy to handle under vacuum conditions, although care should be taken because of its nauseating odor. 

Kelley 181) estimates the entropy at 298 K. as 16.0 e. u. while Latimer 210) estimates 15.1 e. u. We adopt 15.5 e. u. Kubaschewski 206) has reported solid and liquid heat capacity data, a heat of transition of 140 80 cal./gram atom at 643 K., and a heat of melting of 1830 70 cal./gram atom at 983 K. The heat capacity of the solid beta phase and the liquid phase appear to be extraordinarily high, and when combined with vapor pressure data lead to a very unusual Trouton s constant of about 14. Consequently, we have estimated a lower heat capacity of the condensed phases by comparison with calcium. 

From these relationships, the following values are obtained 4 heat of fusion, 3.5 kcal./mol normal boiling point, 233° Trouton s constant, 25.5 cal./deg. mol. The liquid and vapor are both associated.4 Cryoscopic measurements upon benzene solutions give apparent molecular weights ranging from 158 (mol fraction = 0.0016) to 230 (mol fraction = 0.0060). At room temperature the solubility of the compound in benzene is 0.995 g./lOO g. of solvent.3... 

In addition to the properties listed previously,1 the following are characteristic 6 heat of vaporization, 3489 cal./mol Trouton s constant, 30.2 cal./deg. mol critical temperature, —2.05° critical pressure, 42.69 atm. vapor pressure,... 

In my calculations at the time I came across a then unknown property of what is known as Trouton s constant... 

In the following table are given the values of what are known as " Trouton s constants/ so far as they are required for the above three reactions they are calculated, both directly from the observed heats of evaporation and boiling-points and also from a very interesting formula given by Cederberg loc. cii., p. 55),... 

Mobile liquid mp —58" bp +53". Stable up to 500 when pure and totally anhydrous, dj 0.824 df 0.898. nJJ 1.3821. Critical temp 252". Heat of vaporization 7.0 kcal. Mo) vo) at bp — 99.7 ml. Surface tension at mp — 31.09 dynes/cm. Parachor 207.9. Trouton s constant 21.4. Eotvds constant 2.0. Dipole moment in benzene at 25 — 0.50. Dissolves in water, giving a soln with strong reducing properties. Hydrolyzes slowly in aq soln yielding hydrogen, boric acid, and ammonia. 

The deficit of the molar entropy of a liquid with respect to the same substance in the ideal gas phase is a measure of the order existing in the liquid. Trouton s constant, Ayap5 (rb) = AyH T, )/Tb is the negative of this deficit, where is the... 

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