Journal Entry:

Which of the following combinations of thermodynamic functions is true for the mixing of two ideal gases? Assume no reaction occurs, there are no intermolecular forces of attraction or repulsion between any of the gas particles and the process occurs at a constant temperature and pressures.

(A) ΔG=0, ΔS < 0
(B) ΔG=0, ΔS > 0
(C) ΔG<0, ΔS = 0
(D) ΔG<0, ΔS > 0

Learning Intentions

• We will learn how to use representations and models to predict the sign and relative magnitude of the free energy change associated with chemical or physical processes.

• We will learn how to predict whether or not a physical or chemical process is thermodynamically favored (spontaneous) by determination of the signs of both ΔH and ΔS in relation to free energy (ΔG) or direct calculation of ΔG.

• We will learn how to calculate Gibb's Free Energy using two different equations and what conditions to use each one.

Closing Task:

You can determine which equation to use, depending on conditions, to determine Gibb's Free Energy.

Content Standards being covered:

Some physical or chemical processes involve both a decrease in the internal energy of the components under consideration and an increase in the entropy of those components. These processes are necessarily "thermodynamically favored". (E.K. 5.E.2)

If a chemical or physical process is not driven by both entropy and enthalpy changes, then the Gibbs free energy  change can be used to determine whether the process is thermodynamically favored. (E.K. 5.3.E)