| Compound | S°/J K–1 mol–1
at 25 °C |
| H2O(l) | 70 |
| H2O(g) | 189 |
| C6H12(l) | 388 |
Entropy (S) is a measure of the number of different ways that a system can store energy.
As shown in the examples, the absolute entropy of a substance is related to the phase of the substance and its complexity.
Entropy changes in reactions are also related to the phase and chemical nature of the reactants and products.
On completion of this activity you should be able to
- predict the sign and relative magnitude of the entropy change for a reaction from its balanced equation
- verify the prediction by calculation of the entropy change from absolute entropies of the reactants and products