Intermolecular forces in gaseous ammonia and in ammonia – nonpolar gas mixtures

Abstract

Intermolecular potential parameters for ammonia have been determined for the Stockmayer-Kihara function using experimental second virial coefficient, diffusivity and viscosity data of binary mixtures with argon, methane, nitrogen, and oxygen. The parameters Uo/k = 215 PK, core-to-core) = 2.70 A and a* = 0.2 reproduce essentially all of the data nearly w~t h~n expermental error and accurately reproduce pure ammonia transport properties. Upon considering both physical and chemical contributions to the second virial coefficient of ammonia, the apparent standard-state hydrogen-bond enthalpy for chemical dimerization is -3.2 kcal/mole while the vibrational entropy change is 20.2 cal/mole OK, indicating weak association.

Thermodynamic and Transport Properties of Water Vapor at Low Densities

“…The core w'as taken into account by changing only the reduced dipole moment, since the effect of the small core of water on the nonpolar contribution is probably not important. From wTork on ammonia which has a larger core (Lee et al, 1970), the most accurate approximation is to allow the core to affect the distance parameter in the reduced dipole moment according to 2U 0' , { ' + 2 )1,5…”

John M. Prausnitz: Bridging abstractions and realities

“…The subjects ranged from the fundamentally rigorous to the fully applied. Some examples include statistical mechanical partition functions to obtain equations of state, intermolecular force models and molecular simulation, acid‐gas absorption, complex mixtures, and distillation . In other directions, there were 17 articles on adsorption (one of which has been cited 959 times) and seven on weak electrolytes, including one cited 316 times.…”

Calculation of Vapor-Liquid Equilibria for the System NH3-N2-H2-Ar-CH4

“…The constant am in Equation 24reflects the effect of nonpolar intermolecular forces; the constant a(1) reflects the effect of polar forces. The constant a(0) is estimated using a corresponding-states method based on the Kihara-Stockmayer potential (Lee et al, 1970). A reduced constant is defined by aV> = a™ Uos/25 (25) where is the (center-to-center) collision diameter and U0 is the characteristic nonpolar energy.…”

“…From data for argon, nitrogen, and methane we find that czr(0) = 0.2269 X 103, where aro> is in (cc/gmole)2 atm °K1,! ; U0/k is in °K; and is in Á. Nonpolar parameters and U0 for ammonia have been reported (Lee et al, 1970).…”