Molar heat sublimation

Fig. 2.25 The differential heat of adsorption of argon on carbon blacks at 78 K, before and after graphitizalion.. Spheron O, Graphon. , and El denote molar heat of sublimation and of evaporation respectively.

One would expect the enthalpy of sublimation (d) to be the largest of the four quantities cited. Molar heat capacities are quite small, on the order of fractions of a kilojoule per mole-degree. (Remember that specific heats have values of joules per gram-degree.) All of the heats of transition (or latent heats) are positive numbers and on the order of kilojoules per mole. Since the heat of sublimation is the sum of the heat of fusion and the heat of vaporization, AHsubl must be the largest of the three. 

The volatilization process changes the contaminant from a sohd or hquid state, where the molecules are held together by intermolecular forces, into a vapor phase. The molar heats of fusion (A//p, volatilization (AH), and sublimation (AH) are related according to the Bom-Haber cycle by... 

The following thermal values were also obtained —Molar heats of sublimation a-As203, 29,833 /3, 23,676 y, 21,130 calories. Molar heats of fusion a, 15,099 jS, 8942 y, 6396 calories. Molar heat of vaporisation /3, 14,784 calories.1... 

Finally the molar heat of fusion Qsl is obtained in the usual way as the difference between the latent heat of sublimation Qsv and that of evaporation Qlv at the triple point, 862-5° abs.—... 

Calculate the molar entropies Ss and Sg of the crystalline and vapor forms of I2 at 320 K with Eqs. (36) and (37), and obtain the molar heat of sublimation A//sub with Eq. (38). Compare it with the value obtained by the Clausius-Clapeyron method and with any literature values that you can find."... 

Taking the mean molar heat capacities of gaseous hydrogen, iodine and hydrogen iodide as 6.95, 8.02 and 7.14 cal. deg. , respectively, calculate the heat of formation of hydrogen iodide from the gaseous elements at 225 C. The heat of sublimation of solid iodine is 58.5 cal. g. at 25 C. 

Heterogeneous physical equilibria, e.g., between a pure solid and its vapor or a pure liquid and its vapor, can be treated in a manner similar to that just described. If the total pressure of the system is 1 atm., the fugacity of the vapor is here also equivalent to the equilibrium constant. The variation of In/ with temperature is again given by equation (33.16), where MP is now the ideal molar heat of vaporization of the liquid (or of sublimation of the solid) at the temperature T and a pressure of 1 atm. If the total pressure is not 1 atm., but is maintained constant at some other value, the dependence of the fugacity on the temperature can be expressed by equation (29.22), since the solid or liquid is in the pure state thus,... 

Because molecules are more tightly held in a sohd, the vapor pressure of a solid is generally much less than that of the corresponding liquid. Molar heat of sublimation (AHsub) of a substance is the energy (usually in kilojoules) required to sublime one mole of a solid. It is equal to the sum of the molar heats of fusion and vaporization ... 

Define the following terms (a) molar heat of vaporization, (b) molar heat of fusion, (c) molar heat of sublimation. What are their units ... 

How is the molar heat of sublimation related to the molar heats of vaporization and fusion On what law are these relationships based ... 

The molar heats of fusion and sublimation of molecular iodine are 15.27 kJ/mol and 62.30 kJ/mol, respectively. Estimate the molar heat of vaporization of liquid iodine. 

Molar heat of sublimation. The energy (in kilojoules) required to sublime one mole of a sohd. (11.8)... 

AT = Ts — (unless otherwise defined) u = air velocity, miles/hr or ft/sec X = mole fraction of water vapor A = molar heat of sublimation, Btu/mole p = density, Ibm/ft d = frost thickness, ft... 

Intermolecular forces, p. 463 Intramolecular forces, p. 463 Ion-dipole forces, p. 463 Melting point, p. 495 Molar heat of fusion (A7/f s), p. 496 Molar heat of sublimation p. 497... 

The standard enthalpy of formation of gaseous molecular iodine is 62.4 kJ/mol. Use this information to calculate the molar heat of sublimation of molecular iodine at 25°C. 

Question Silver has the FCC crystal structure with a unit cell parameter o = 4.09 A. Each atom is coordinated to 12 neighbors. Given that the molar heat of sublimation for Ag is 284kJ/mol, estimate the surface energy (in J/cm ) of the Ag (100) surface. 

Molar heat of sublimation (AHsubXp.415 Molar heat of vaporization (AHvapX P-410 Phase, p. 408... 

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