Laws of thermodynamics

Macrostates and microstates
Quasistatic and reversible processes
First law of thermodynamics / internal energy
More on internal energy
Work from expansion
PV-diagrams and expansion work
Proof: U = (3/2)PV or U = (3/2)nRT
Work done by isothermic process
Carnot cycle and Carnot engine
Proof: Volume ratios in a Carnot cycle
Proof: S (or entropy) is a valid state variable
Thermodynamic entropy definition clarification
Reconciling thermodynamic and state definitions of entropy
Entropy intuition
Maxwell's demon
More on entropy
Efficiency of a Carnot engine
Carnot efficiency 2: Reversing the cycle
Carnot efficiency 3: Proving that it is the most efficient