Gibbs Free Energy Quiz and Flashcards: Reaction Direction Study Guide

Study Notes

The Second Law of Thermodynamics

The second law of thermodynamics states that the entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process.
Entropy is a measure of the disorder or randomness in a system.
Heat always flows from a hot object to a cold object, which is consistent with the second law of thermodynamics.

Entropy and Its Implications

In a closed system, entropy increases over time.
Some energy transformations are irreversible, which is an implication of the second law of thermodynamics.
Entropy is often referred to as the measure of disorder.

Predicting Spontaneity of a Process

The thermodynamic quantity used to predict the spontaneity of a process is Gibbs free energy (∆G).
At equilibrium, the value of ∆G for a process is zero.
∆G < 0 shows a spontaneous process at a constant temperature and pressure.

Gibbs Free Energy and Its Relationship

The equation ∆G = ∆H – T∆S correctly represents the relationship between Gibbs free energy, enthalpy, and entropy.
Joules (J) is the unit typically used for Gibbs free energy.
A spontaneous reaction is indicated by a negative ∆G.
Factors that affect the spontaneity of a reaction according to Gibbs free energy include:
- Temperature (T)
- Enthalpy change (∆H)
- Entropy change (∆S)

Gibbs Free Energy Equations

The equation ∆G = RT in JK relates to the spontaneity of a process.
The equation ∆G = ∆H – T∆S correctly represents Gibbs free energy (∆G).

Examples of Spontaneous and Non-Spontaneous Processes

Rusting of iron is an example of a spontaneous process.
Melting of ice cubes at -50C and 1atm is an example of a non-spontaneous process.
Ice formation is another example of a non-spontaneous process.
Arranging books in a shelf by height does not show an increasing entropy.
A type of process that absorbs heat from the surroundings is endothermic.

Description

Test your understanding of Gibbs free energy and its relation to reaction direction, equilibrium, and spontaneity. Learn how to use ∆G to determine the direction of a reaction and understand the significance of ∆G = 0. This quiz covers the fundamental concepts of thermodynamics in general chemistry.