CHAPTER16

Assumptions the mixture is ideal and thus raoults law

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: de Ptotal PNH3,gas side Ptotal 2.22 kPa 1090.25 kPa 1088.03 kPa 1090.25 kPa 0.0020 0.9980 Discussion Note that the gas phase consists almost entirely of ammonia, making this mixture very suitable for absorption refrigeration. SUMMARY An isolated system is said to be in chemical equilibrium if no changes occur in the chemical composition of the system. The criterion for chemical equilibrium is based on the second law of thermodynamics, and for a system at a specified temperature and pressure it can be expressed as 1dG2 T, P 0 For reacting systems that consist of ideal gases only, the equilibrium constant KP can be expressed as KP e G*1T 2&gt;RuT where the standard-state Gibbs function change G*(T) and the equilibrium constant KP are defined as G* 1T2 nC gC 1T2 * nD gD 1T2 * nA g A 1T2 * nB gB 1T2 * For the reaction nAA nBB nCC nDD and KP P nC P nD C D P nA P nB A B where the n's are the stoichiometric coefficients, the equilibrium criterion can be expressed in terms of the Gibbs functions as nC g C nD g D nA g A nB g B 0 which is valid for any chemical reaction regardless of the phases involved. Here, Pi's are the partial pressures of the components in atm. The KP of ideal-gas mixtures can also be expressed in terms of the mole numbers of the components as KP N nC N nD P n C D b nA nB a N A N B N total 816 | Thermodynamics of a pure substance are in equilibrium when each phase has the same value of specific Gibbs function. That is, gf gg In general, the number of independent...
View Full Document

This note was uploaded on 06/15/2009 for the course MAE 3311 taught by Professor Hajisheik during the Summer '08 term at UT Arlington.

Ask a homework question - tutors are online