Entropy S

Extracted from TsederLerg, Popov, et al., Theimodynamic and Theimophysical Propeities of Helium, Atomizdat, Moscow, 1969, and NBS-NSF TT 50096, 1971. Copyriglit material. Reproduced hy permission. This source contains entries for many more temperatures and pressures than can he reproduced here, v = volume, mVkg h = enthalpy, kj/kg s = entropy, kJ/(kg-K). 

N, Number of particles P, Pressure V, Volume T, Temperature E, Energy fi. Chemical potential A, Helmholtz free energy S, Entropy G, Gibbs free energy. 

The second law of thermodynamics also consists of two parts. The first part is used to define a new thermodynamic variable called entropy, denoted by S. Entropy is the measure of a system s energy that is unavailable for work.The first part of the second law says that if a reversible process i f takes place in a system, then the entropy change of the system can be found by adding up the heat added to the system divided by the absolute temperature of the system when each small amount of heat is added ... 

Because the gas in the Carnot cycle starts and ends at the same state, the system s entropy does not change during a cycle. Now apply the second law to the universe for the case of the Carnot cycle. Because the processes are reversible, the entropy of the universe does not change by Equation 2b. This can be written ... 

A S Entropy change The change in molecular randomness during a reaction. When AS° is negative, randomness decreases when AS° is positive, randomness increases. 

R thermal resistance x specific entropy S entropy t time T temperature u specific internal energy U internal energy v specific volume velocity V volume W shaft work x coordinate distance... 

Figure 230. Direct thermal energy storage (Q thermal energy, S entropy, T temperature)...

S Entropy (kJ-K-1, kJkg-1-K-1, kJkmol-1-K-1), or number of streams in a heat exchanger network (-), or reactor selectivity (-), or reboil ratio for distillation (-), or selectivity of a reaction (-), or slack variable in optimization (units depend on application), or solvent flowrate (kg s-1, kmol-s-1), or stripping factor in absorption (-)... 

Figures 13.2,13.3,13.4, 13.5,13.6,13.11 and 13.12 are reproduced with permission from the Royal Society of Chemistry from Chemical Society Reviews, 31, Krishna, R., Smit, B., and Calero, S., Entropy effects during sorption of alkanes in zeolites, p. 185-194, Copyright The Royal Society of Chemistry (2002) http //www.rsc.org/Puhlishing/Joumals/ CS/article.asp doi=bl01267n Figures 13.7 and 13.8 are reprinted with permission from the Journal of Physical Chemistry B, 101 (8), Eder, E., Lercher, J.A., On the role of the pore size and tortuosity for sorption of alkanes in molecular sieves, p. 1273-1278,...

S Entropy on the tetrahedron approximation. If the treatment is extended to the case of a tetrahedral cluster, diis immediately raises the number of required equations to (2 ) variables. As already indicated, the pair approach is not sufficient to adequately describe the f.c.c. lattice, where an additional variable Zijta is needed where i, j, k, I can take values 1, 2, 3... corresponding to various atoms or vacancies. The energy expression corresponding to the tetiahedra is then given by... 

Johari G.P. (2000) An equilibrium supercooled liquid s entropy and enthalpy in the Kauzmann and the third law extrapolations, and a proposed experimental resolution. /. Chem. Phys. 113, 751-761. 

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