The Entropy of Deuterium Oxide and the Third Law of Thermodynamics. Heat Capacity of Deuterium Oxide from 15 to 298°K. The Melting Point and Heat of Fusion

1936 ◽  
Vol 58 (10) ◽  
pp. 1829-1834 ◽  
Author(s):  
Earl A. Long ◽  
J. D. Kemp
Keyword(s):  
Heat Capacity ◽  
Melting Point ◽  
Deuterium Oxide ◽  
Heat Of Fusion ◽  
The Third ◽  
Third Law Of Thermodynamics ◽  
Third Law

Heat Capacity, Entropy, and Free Energy of Rubber Hydrocarbon

1936 ◽  
Vol 9 (2) ◽  
pp. 264-274 ◽  
Author(s):  
Norman Bekkedahl ◽  
Harry Matheson
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Heat Of Formation ◽  
The Third ◽  
Free Energy Of Formation ◽  
Third Law Of Thermodynamics ◽  
Third Law ◽  
Lower Temperature ◽  
Energy Of Formation

Abstract The best method for obtaining the free energy of formation of rubber is by making use of the third law of thermodynamics. This makes necessary the determination of heat-capacity values of rubber from room temperature down to temperatures sufficiently low to apply an empirical formula for obtaining the values below this lower temperature. From these heat-capacity values the entropy may be obtained. Then from this latter value, along with the entropy values of carbon (graphite) and gaseous hydrogen and the heat of formation of rubber, a reliable value for the free energy of formation of rubber may be calculated. Several investigators have previously determined the heat capacities of rubber, but their observations were not made at temperatures sufficiently low to permit accurate extrapolation to the absolute zero in order to apply the third law. Furthermore, in the previous work the possibility that rubber at low temperatures might exist either as a metastable amorphous form or as a crystalline form was not clearly recognized. In the present investigation the aim was not only to extend the temperature range but also to obtain data of a higher order of accuracy than that previously reported.

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.

Sign in / Sign up

Export Citation Format

Share Document