Applications of Thermodynamics

Eleven topics on what drives change. Entropy and its absolute values, Gibbs free energy and thermodynamic favorability, why a favored reaction can still be slow, how free energy sets the equilibrium constant, dissolution and coupled reactions, and the whole of electrochemistry — galvanic and electrolytic cells, cell potential and free energy, the Nernst equation, and Faraday’s law.

Topics

9.1

Introduction to Entropy

Absolute Entropy and Entropy Change

Gibbs Free Energy and Thermodynamic Favorability

Thermodynamic and Kinetic Control

Free Energy and Equilibrium

Free Energy of Dissolution

Coupled Reactions

Galvanic and Electrolytic Cells

Cell Potential and Free Energy

Cell Potential Under Nonstandard Conditions

Electrolysis and Faraday's Law

Lesson

Diag

locked

Equations For every problem in this unit

Entropy change

ΔS° = Σ S°(products) − Σ S°(reactants), weighted by coefficients

Gibbs free energy

ΔG = ΔH − TΔS; favored when ΔG < 0

Favorability vs rate

ΔG sets favorability; activation energy sets rate (a favored reaction can be slow)

Free energy and K

ΔG° = −RT ln K; large K → negative ΔG°; ΔG° = 0 → K = 1

Dissolution

ΔG = ΔH − TΔS; solution enthalpy = lattice cost + hydration

Coupling

a favorable reaction drives an unfavorable one through a shared intermediate; ΔG values sum

Cell setup

oxidation at anode, reduction at cathode; electrons through the wire, ions through the salt bridge

Potential and free energy

ΔG° = −nFE°_cell; positive E° is favorable; E° is intensive

Nernst

E = E° − (0.05916/n) log Q at 25°C

Faraday's law

charge = current × time; moles e− = charge/F; then moles metal, then grams

Unit 1 tools

Challenge bank

1 / 60

60 open-ended problems.

Read the question, work it out, then flip the card to compare your reasoning to the worked solution. Mark each card so you can return to the ones that still bite.

Question

Tap card to reveal explanation

Worked solution

Tap card to return to question

Cumulative assessment

Test the unit.

Twenty mixed items pulled from across all 11 topics. Identifies which misconceptions still bite when you cannot see which topic the question came from.