Yash Paul Handa

Compositions, enthalpies of dissociation and heat capacities in the range 85 to 270 K for clathrate hydrates of methane, ethane, and propane, and enthalpy of dissociation of isobutane hydrate, as determined by a heat-flow calorimeter

Abstract Compositions, enthalpies of dissociation, and heat capacities in the range 85 to 270 K were determined for the first time for clathrate hydrates of methane, ethane, and propane using a Tian-Calvet heat-flow calorimeter. The enthalpy of dissociation was also measured for isobutane hydrate. The enthalpy of dissociation for the process (hydrate = ice + gas) at 273.15 K and 101.325 kPa is (18.13±0.27) kJ·mol −1 for CH 4 ·6.00H 2 O, (25.70±0.37) kJ·mol −1 for C 2 H 6 ·7.67H 2 O, and (27.00±0.33) kJ·mol −1 for C 3 H 8 ·17.0H 2 O. The enthalpy of dissociation of isobutane hydrate at 245 K is (31.07±0.20) kJ·mol −1 . Molar heat-capacity contributions from the guests to their hydrates were found to be comparable with the ideal-gas heat capacity for methane and somewhat higher for ethane and propane.

Calorimetric determinations of the compositions, enthalpies of dissociation, and heat capacities in the range 85 to 270 K for clathrate hydrates of xenon and krypton☆

A calorimetric technique is described which gives for a single sample-loading the composition, enthalpy of dissociation, and heat capacities of gas hydrates. Heat capacities in the range 85 to 270 K and enthalpies of dissociation were obtained for structure I: Xe · 5.90H2O, and structure II: Kr · 6.10H2O, clathrate hydrates. Molar heat-capacity contributions from xenon and krypton to their hydrates are less than 3R each. The standard enthalpy of dissociation for the process (hydrate = ice + gas) at 273.15 K and 101.325 kPa is (26.50 ± 0.17) kJ · mol−1 for Xe · 5.90H2O and (19.54 ± 0.24) kJ · mol−1 for Kr · 6.10H2O.

Volume changes on mixing two liquids: A review of the experimental techniques and the literature data☆

Abstract Various experimental techniques used for determining density of pure liquids and their mixtures and for volume changes on mixing (VE) are reviewed. Some guidelines are given for precise determination of VE and for correlating the data to a suitable smoothing function. The available literature data on VE for the test system cyclohexane + benzene is critically evaluated and a smoothing equation is given which represents the three best sets of VE data (a total of 164 points) for the test system, with a standard deviation of 0.0016 cm3 mol−1. A table gives smoothed VE data over the entire mole fraction range for about 1000 mixtures, most of them at more than one temperature, reported over the last ten years. Other important information included in the table is the method and temperature(s) of measurement, number of data points, and shape of the VE against mole fraction curve. Finally a brief summary is given of the noteworthy observations reported in the literature.

Ultrasonic speeds and isentropic compressibilities for (decan-1-ol + n-alkane) at 298.15 K☆

Measurements of ultrasonic speed were carried out for hexan-1-ol+n-pentane, +n-hexane, +n-octane, and +n-decane at 298.15 K. The measurements were made over the entire mole-fraction range with special attention paid to the region highly dilute with respect to hexan-1-ol. The results were combined with excess volumes VmE from our previous studies to yield excess isentropic compressibilities KSE and the partial molar excess quantities KS.iE = −(∂ViE∂p)s. A qualitative discussion of the results is presented.

Calibration and testing of a Tian-Calvet heat-flow calorimeter Enthalpies of fusion and heat capacities for ice and tetrahydrofuran hydrate in the range 85 to 270 K☆

Abstract An automated Tian-Calvet heat-flow calorimeter operating under digital control is described. It was calibrated in the range 85 to 290 K using synthetic sapphire. Procedures for measuring heat capacity and enthalpy of fusion are described. The accuracy of the heat-capacity measurements is 1.5 per cent between 85 and 100 K and 1 per cent above 100 K. Enthalpies of fusion are accurate to 1 per cent. Enthalpies of fusion and heat capacities between 85 and 270 K are reported for ice and tetrahydrofuran hydrate and compared with literature values.

Thermodynamics of aqueous mixtures of nonelectrolytes. IV. Excess volumes of water-acetonitrile mixtures from 15 to 35°C

Excess volumes of water-acetonitrile mixtures were obtained from measurements of density over the entire mole fraction range and at 5 degree intervals from 15 to 35°C. Partial molar excess volumes at the five temperatures, excess coefficients of thermal expansion at 25°C and partial molar excess expansibilities at 25°C were derived from the results. The values of the various volumetric properties are compared with data from the literature.

Thermodynamic properties of binary mixtures containing esters. I. Analysis of the properties of n-alkanoate + n-alkane and n-alkanoate + n-alkanoate mixtures in terms of a quasichemical group-contribution model

Abstract The thermodynamic properties of n-alkanoate + n-alkane and + n-alkanoate binary liquid mixtures are examined on the basis of the group-surface interaction version of the Guggenheim-Barker quasichemical pseudolattice theory. All the data available in the literature for liquid—vapor and liquid—liquid equilibria, excess enthalpies and activity coefficients at infinite dilution are taken into consideration. Using only four alkyl-group increments, in addition to the two group-interaction parameters for methyl ethanoate, the model provides a fairly consistent description of the properties of the mixtures as functions of composition, temperature and chain length. The results are discussed in comparison with other classes of systems investigated previously (alkanones and alkanals).

Thermodynamic properties of binary mixtures containing ketones III. Excess enthalpies of n-alkanes + some aliphatic ketones

Abstract Flow-calorimetric measurements of excess enthalpies at 298.15 K are reported for n -pentane + 2-butanone, + 2-pentanone, and +3-pentanone, and for n -heptane, n -octane, and n -decane with each of the same set of aliphatic ketones.

Thermodynamics of aqueous mixtures of nonelectrolytes. V. Isobaric heat capacities and ultrasonic speeds for water + ethanenitrile mixtures at 25°C

Abstract Volumetric heat capacities and ultrasonic speeds were measured at 25°C for water + ethanenitrile mixtures over the entire mole fraction range using a flow microcalorimeter and pulse-echo-overlap equipment, respectively. Excess volumes and coefficients of thermal expansion reported previously were used in conjunction with the present data to yield isobaric and isochoric heat capacities, and isentropic and isothermal compressibilities. The present study supports the view that ethanenitrile acts as a structure breaker.

Structure of oxygen clathrate hydrate by neutron powder diffraction

AbstractOxygen hydrate was prepared by reacting oxygen with deuteriated ice at high pressure. Its structure was examined with powder neutron diffraction. It was found to crystallize in the cubic space group