Protonation of azobenzene derivatives. I. Methyl orange and ortho-methyl orange

1973 ◽  
Vol 26 (5) ◽  
pp. 1005 ◽  
Author(s):  
PD Bolton ◽  
J Ellis ◽  
KA Fleming ◽  
IR Lantzke
Keyword(s):  
Heat Capacity ◽  
Methyl Orange ◽  
Aqueous Solutions ◽  
Standard Enthalpy ◽  
Acidity Constants ◽  
Temperature Range ◽  
Heat Capacity Changes ◽  
Azobenzene Derivatives

Thermodynamic acidity constants have been measured over the temperature range 5-50� for aqueous solutions of sodium 4?-dimethylaminoazobenzene- 4-sulphonate (methyl orange) and sodium 4?-dimethylaminoazobenzene-2- sulphonate (ortho-methyl orange). From these data values of the standard enthalpy, entropy, and heat capacity changes have been calculated for these compounds. These results are discussed in conjunction with previous spectrophotometric and other data with reference to the nature of the equilibrium systems involved in these protonation reactions. It is concluded that existing evidence does not allow an unequivocal assignment of the sites of protonation of these and related molecules.

scholarly journals Heat Capacity Changes of Some Sodium Alkylsulfates in Aqueous Solutions

1972 ◽  
Vol 45 (9) ◽  
pp. 2939-2940 ◽  
Author(s):  
Kunio Tamaki ◽  
Yoshio Isomura ◽  
Y\={o}ko Ohara
Keyword(s):  
Heat Capacity ◽  
Aqueous Solutions ◽  
Heat Capacity Changes ◽  
Sodium Alkylsulfates

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.

Aqueous nonelectrolyte solutions. Part XVI. Formula of deuterium sulfide D-hydrate and its dissociation thermodynamic functions

2000 ◽  
Vol 78 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Colin W Clarke ◽  
David N Glew
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Functions ◽  
Standard Enthalpy ◽  
Approximate Formula ◽  
Deuterium Oxide ◽  
Equilibrium Constants ◽  
Hydrate Dissociation ◽  
Quadruple Point ◽  
Dissociation Equilibrium ◽  
Heat Capacity Changes

A method has been devised to approximate both the hydrate formula number n and the standard thermodynamic functions for hydrate dissociation from the temperature change of the hydrate former fugacity along a univariant three-phase (hl1g) equilibrium line. Thermodynamic equations are derived, their validity discussed, and an iterative method for their solution is described. The univariant (hl1g) equilibrium dissociation of deuterium sulfide D-hydrate (D2S·nD2O phase h) into gaseous deuterium sulfide (g) and liquid deuterium oxide (l1) has been treated to give approximate formulae and dissociation constants at 58 temperatures from 2.798 to 30.666°C. Dissociation equilibrium constants Kp(h–> l1g) have been represented as a function of temperature by a four-parameter equation which yields both values and standard errors (i) for ΔHot(h–> l1g) and ΔCpot(h–> l1g) the standard enthalpy and heat capacity changes for D-hydrate dissociation and (ii) for n = r the approximate formula number of the D-hydrate at each experimental temperature. The formula D2S·6.115D2O with standard error 0.018D2O is found for deuterium sulfide D-hydrate at lower quadruple point Q(hs1l1g) 3.392°C; an approximate formula D2S·5.840D2O with SE 0.019D2O is found at upper quadruple point Q(hs1l2g) 30.770°C. Key words: clathrate D-hydrate of deuterium sulfide, deuterium sulfide D-hyfrate, formula of deuterium sulfide D-hydrate, thermodynamics of clathrate hydrate dissociation, dissociation equilibrium constant of deuterium sulfide D-hydrate, standard enthalpy, and heat capacity changes for dissociation of deuterium sulfide D-hydrate.

THE HEAT CAPACITY OF AQUEOUS SOLUTIONS OF HYDROFLUORIC ACID

1946 ◽  
Vol 24b (2) ◽  
pp. 51-56 ◽  
Author(s):  
T. Thorvaldson ◽  
E. C. Bailey
Keyword(s):  
Heat Capacity ◽  
Aqueous Solutions ◽  
Specific Heat ◽  
Hydrofluoric Acid ◽  
Temperature Range ◽  
Apparent Molal Heat Capacity

The heat capacity of aqueous solutions of hydrofluoric acid varying in concentration from 0.55 to 48% was determined over the temperature range 18° to 20 °C. The respective values for the specific heat varied between 0.996 and 0.718 cal. per gm. The values obtained are consistent among themselves but differ markedly from those found in the literature. The apparent molal heat capacity of the solute over this range of concentration and temperature was calculated and compared with values obtained from the data of other experimenters.

scholarly journals Heat Capacity Changes of Alkyl-substituted Ammonium Chlorides in Aqueous Solutions

1975 ◽  
Vol 48 (11) ◽  
pp. 3018-3020 ◽  
Author(s):  
Kunio Tamaki ◽  
Satoru Yoshikawa ◽  
Mitsuyoshi Kushida
Keyword(s):  
Heat Capacity ◽  
Aqueous Solutions ◽  
Heat Capacity Changes
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