Hydrogen Sulfide. The Heat Capacity and Vapor Pressure of Solid and Liquid. The Heat of Vaporization. A Comparison of Thermodynamic and Spectroscopic Values of the Entropy

1936 ◽  
Vol 58 (5) ◽  
pp. 831-837 ◽  
Author(s):  
W. F. Giauque ◽  
R. W. Blue
Keyword(s):  
Heat Capacity ◽  
Hydrogen Sulfide ◽  
Vapor Pressure ◽  
Heat Of Vaporization

Aqueous nonelectrolyte solutions. Part XVII. Formula of hydrogen sulfide hydrate and its dissociation thermodynamic functions

2000 ◽  
Vol 78 (9) ◽  
pp. 1204-1213 ◽  
Author(s):  
David N Glew
Keyword(s):  
Heat Capacity ◽  
Hydrogen Sulfide ◽  
Vapor Pressure ◽  
Standard Enthalpy ◽  
Approximate Formula ◽  
Saturation Vapor Pressure ◽  
Hydrate Dissociation ◽  
Quadruple Point ◽  
Heat Capacity Changes ◽  
Saturation Vapor

Literature data for the saturation vapor pressure P(hl1g) of hydrogen sulfide hydrate with water, at 43 temperatures between quadruple points Q(hs1l1g) at –0.4°C and Q(hl1l2g) at 29.484°C, are properly represented by a six-parameter equation to give a standard error (SE) of 0.13% on a hydrate pressure measurement of unit weight. Equilibrium hydrogen sulfide and water fugacities and the gas and aqueous phase compositions are derived using the Redlich–Kwong equation of state. Literature data for the saturation vapor pressure P(hs1g) of hydrogen sulfide hydrate with ice, at 15 temperatures between –1.249 and –21.083°C, are properly represented by a two-parameter equation to give a SE of 0.26% on a single hydrate pressure measurement. Quadruple point Q(hs1l1g) is evaluated at temperature –0.413° with SE 0.042°C and at pressure 94.7 with SE 0.26 kPa. Using the thermodynamic method, described for deuterium sulfide D-hydrate, the equilibrium fugacities of hydrogen sulfide are used to define 43 equilibrium constants Kp(h[Formula: see text]l1g) for hydrate dissociation into water and hydrogen sulfide gas. The temperature dependence of ln Kp(h[Formula: see text]l1g) is represented by a three-parameter thermodynamic equation which gives both values and standard errors (i) for Kp(h[Formula: see text]l1g), and for δHot(h[Formula: see text]l1g) and δCpot(h[Formula: see text]l1g), the standard enthalpy and heat capacity changes for hydrate dissociation and (ii) for n = r the approximate formula number of the hydrate H2S·nH2O at each experimental temperature. The formula H2S·6.119H2O with standard error 0.029H2O is found for hydrogen sulfide hydrate with water at lower quadruple point Q(hs1l1g) –0.413°C: an approximate formula H2S·5.869H2O with SE 0.026H2O is found at upper quadruple point Q(hl1l2g) 29.484°C. These estimates for the formula of hydrogen sulfide hydrate at its quadruple points are not significantly different from those found for the deuterium sulfide D-hydrate.Key words: clathrate hydrate of hydrogen sulfide, hydrogen sulfide hydrate, formula of hydrogen sulfide hydrate, thermodynamics of clathrate hydrate dissociation, dissociation equilibrium constant of hydrogen sulfide hydrate, standard enthalpy and heat capacity changes for dissociation of hydrogen sulfide hydrate.

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.

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