Ethylene. The Heat Capacity from 15°K. to the Boiling Point. The Heats of Fusion and Vaporization. The Vapor Pressure of the Liquid. The Entropy from Thermal Measurements Compared with the Entropy from Spectroscopic Data

1937 ◽  
Vol 59 (7) ◽  
pp. 1264-1268 ◽  
Author(s):  
Clark J. Egan ◽  
J. D. Kemp
Keyword(s):  
Heat Capacity ◽  
Vapor Pressure ◽  
Boiling Point ◽  
Spectroscopic Data ◽  
Thermal Measurements

Estimation of heats of vaporization for non associating organic liquids from the boiling points at various pressures

1986 ◽  
Vol 64 (4) ◽  
pp. 635-640 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Heat Capacity ◽  
Vapor Pressure ◽  
Boiling Point ◽  
Room Temperature ◽  
Quadratic Function ◽  
Organic Liquids ◽  
Heat Of Vaporization ◽  
Boiling Points ◽  
Temperature And Pressure ◽  
Heats Of Vaporization

At any pressure the heat of vaporization can be expressed as a quadratic function of the boiling point at that pressure. A seven parameter equation expressing the simultaneous dependence on boiling point and pressure can be fitted to the data; six pressures from 1 to 760 Torr (1 Torr = 133.3 Pa) were used. ΔHvap = b11 + b12 In (p) + b13p + (b21 + b22 In (p))tbp + (b31 + b32 In (p))tbp2. This relationship served as a guide for developing a relationship between vapour pressure at 25 °C and the calorimetric heat of vaporization, and also a relationship between vapor pressure at 25 °C and the boiling point at some other pressure. Parameters for both these relationships could be derived from the parameters obtained for ΔHvap as a function of temperature and pressure. A third method was developed starting from an equation for vapor pressure and fitting to the heat of vaporization, the heat capacity of vaporization, and at least one t,p point. These methods allow the estimation of the vapor pressure at room temperature from very meager data. The problems of errors in estimated values are discussed.

THE THIRD LAW ENTROPY AND STRUCTURE OF IRON PENTACARBONYL

1959 ◽  
Vol 37 (11) ◽  
pp. 1923-1929 ◽  
Author(s):  
A. J. Leadbetter ◽  
J. E. Spice
Keyword(s):  
Heat Capacity ◽  
Spectroscopic Data ◽  
Room Temperature ◽  
Iron Pentacarbonyl ◽  
Ideal Gas ◽  
Heat Of Fusion ◽  
Anomalous Absorption ◽  
The Third ◽  
Thermal Measurements ◽  
Third Law

The heat capacity of solid and liquid iron pentacarbonyl has been measured from 20° to 290°K. The heat of fusion was also measured and found to be 3161 ± 3 cal/mole. From an investigation of the change of temperature of the sample during melting the triple point of iron pentacarbonyl was estimated to be 253.15°K and the purity of the sample 99.9 mole%. An anomalous absorption of energy amounting to 4.8 cal/mole was observed at about 230°K; this is shown to be due to an unknown impurity in the sample. The vapor pressure of the liquid was measured in the vicinity of room temperature and from these results the heat of vaporization at 25 °C was estimated to be 9.1 ± 0.1 kcal/mole.The entropy of iron pentacarbonyl as an ideal gas at 1 atm pressure and 25 °C computed from the thermal measurements is 106.4 ± 0.8 cal/mole deg. Comparison of this quantity with values calculated from spectroscopic data indicates that the iron pentacarbonyl molecule has the form of a trigonal bipyramid rather than that of a square pyramid.

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