Cracking the AP Chemistry Exam
Content Review for the AP Chemistry Exam
Big Idea #5: Laws of Thermodynamics and Changes in Matter
GIBBS FREE ENERGY
The Gibbs free energy, or simply free energy, G, of a process is a measure of whether or not the process will proceed without the input of outside energy. A process that occurs without outside energy input is said to be thermodynamically favored, while one that does not is said to be thermodynamically unfavored. Prior to this year’s exam, the terms spontaneous and nonspontaneous were used to described thermodynamically favored and unfavored reactions, respectively. It would be good for you to be familiar with both sets of terms, although this text will use the updated terms.