Thermodynamics and Electrochemistry
Thermodynamic favorability depends on the universe’s entropy change or, at constant temperature and pressure, the system’s Gibbs-energy change. Favorable does not mean fast.
- Exam weight
- 7–9%
- Topics
- 11
Introduction
Thermodynamic favorability depends on the universe’s entropy change or, at constant temperature and pressure, the system’s Gibbs-energy change. Favorable does not mean fast.
Standard free energy links to equilibrium through K, while current composition enters through Q. Coupling can produce a favorable net process only when equations and a physical intermediate genuinely connect.
Electrochemical cells translate redox free energy into potential or use an external source to drive change. Charge, electron stoichiometry, units, and cell direction must remain consistent.
Introduction to Entropy
What molecular changes tend to increase entropy?
Entropy tends to rise when energy and matter can occupy more accessible arrangements, especially with greater particle dispersal, phase freedom, volume, or independently moving particles.
Entropy counts accessible arrangements
Compare the number of ways particles and energy can be distributed without equating disorder with messiness.
Particles or energy occupy fewer allowed arrangements.
The same macroscopic constraints permit more arrangements.
Entropy follows multiplicity under stated constraints.
Read this figure without the graphic
Entropy counts accessible arrangements. The figure connects few microstates, many microstates, same macroscopic constraints so the relationship can be read without relying on color alone.
| Representation | What to read |
|---|---|
| few microstates | starting evidence or quantity |
| many microstates | intermediate relationship |
| same macroscopic constraints | result or conclusion |