Physical Chemistry , 1st ed.

where the S(products) and S(reactants) represent the absolute entropy of the chemical species involved in the process. If standa ...

its form in terms of number of moles of substance, gives us a way to determine Sfor a process where temperature is changing: S ...

The second step is to evaluate the change in entropy at the reference tem- perature, 298 K. We will label this S 2. This was, ...

The second part is for the reaction at standard conditions. Again, that has already been evaluated in Example 3.7, and is S 2 ...

3.2 Limits of the First Law 3.1.Decide whether the following processes will be sponta- neous, and why. The “why” can be general, ...

3.23.4.00 L of Ar and 2.50 L of He, each at 298 K and 1.50 atm, were mixed isothermically and isobarically. The mix- ture was th ...

hale. Assuming ideal gas behavior, what’s the change in en- tropy of the air? Assume a temperature of 37°C. 3.44.Set up expressi ...

4 8989 W E STARTED THE LAST CHAPTER with the question, “Will a process occur spontaneously?’’ Although we introduced the concept ...

as a measure of spontaneity is limited in application, since it applies to isolated systems on which no work is done and which a ...

For clarity, we are dropping the “ext” label on the pressure variable. The two pdVterms cancel to give us dHVdpTdS 0 for a sp ...

Note that in the above example, all of the processes maybe spontaneous. However, only the last two mustbe spontaneous by the law ...

The state functions U,H,A, and Gare the only independent energy quan- tities that can be defined using p,V,T, and S. It is impor ...

Making the same substitution for dS dq/T, and also substituting for the de- finition ofpVwork, we get dU p dVT dSdwnon-pV If t ...

or, integrating: AUTS (4.12) Similarly, for the Gibbs free energy: GHTS dGdHT dSS dT dGdHT dS for an isothermal chan ...

The 2s are from the stoichiometry of the balanced chemical reaction. We get rxnS326.68 J/K (Is this reasonable, knowing what ...

But from the natural variable equation, we know that dUT dSp dV If we compare these two equations, the terms multiplying the d ...

Other relationships can be derived from the other natural variable equa- tions. From dH:  H S  p T (4.20)  H p  S V (4 ...

to get H: HG TS If we know how Gbehaves with respect to its natural variables, we know ( G/ T)p. This partial derivative is equ ...

The derivative with respect to xof the derivative ofFwith respect to yis equal to the derivative with respect to yof the derivat ...

from equation 4.29. Similarly, for the other energies:  V  U S  VS  S  U V  SV (4.31)  V  A T  VT  T ...