Thermodynamics & Kinetics

Classical thermodynamics and chemical kinetics - the macroscopic foundation before statistical mechanics.

🔥 Macroscopic vs Microscopic Perspectives

Thermodynamics and Statistical Mechanics describe the same physical phenomena from complementary perspectives:

Thermodynamics (Macroscopic)

• Deals with bulk properties: P, V, T, S
• Empirical laws from experiments
• No reference to atomic structure
• Exact within its domain
• This course

Statistical Mechanics (Microscopic)

• Derives bulk properties from atomic/molecular behavior
• Uses probability and ensembles
• Requires knowledge of microscopic interactions
• Explains "why" behind thermodynamic laws
• Statistical Mechanics course

Recommended path: Study thermodynamics first for phenomenological understanding, then statistical mechanics to see the microscopic origin of thermodynamic laws.

Course Overview

MIT 5.60 is a comprehensive first-year graduate course covering classical thermodynamics and chemical kinetics. The course develops thermodynamics from its fundamental postulates, explores applications to phase equilibria and chemical reactions, then transitions to reaction kinetics and dynamics.

Unlike statistical mechanics which starts from microscopic principles, thermodynamics is built on a small number of empirical laws (0th, 1st, 2nd, 3rd laws) that have been verified by countless experiments. These laws are universal - they apply to all systems regardless of microscopic details.

The course includes chemical kinetics - the study of reaction rates and mechanisms. This is particularly valuable for plasma chemistry, combustion, atmospheric chemistry, and understanding non-equilibrium processes.

The Four Laws of Thermodynamics

Zeroth Law: Temperature

If system A is in thermal equilibrium with system C, and system B is in thermal equilibrium with system C, then A and B are in thermal equilibrium with each other. This defines temperature as an equilibrium property and allows thermometry.

First Law: Energy Conservation

$dU = \delta Q - \delta W$

Energy is conserved. The change in internal energy U equals heat added minus work done by the system. δQ and δW are path-dependent (inexact differentials), but dU is a state function (exact differential).

Second Law: Entropy Always Increases

$dS \geq \frac{\delta Q}{T}$

The entropy S of an isolated system never decreases. For reversible processes dS = δQ/T (equality), for irreversible processes dS > δQ/T. This defines the arrow of time and limits efficiency of heat engines.

Third Law: Absolute Zero

$S(T \to 0) \to 0 \text{ for perfect crystal}$

The entropy of a perfect crystal at absolute zero is zero. Equivalently: absolute zero cannot be reached in a finite number of steps. This provides an absolute scale for entropy.

Key Concepts & Topics

Thermodynamic Potentials

• Internal energy U(S,V,N)
• Enthalpy H = U + PV (constant P processes)
• Helmholtz free energy F = U - TS (constant T)
• Gibbs free energy G = H - TS (constant T,P)
• Maxwell relations from exact differentials
• Legendre transforms between potentials

Phase Equilibria

• Phase diagrams: P-T, P-V, T-S
• Clausius-Clapeyron equation
• Phase coexistence: μ₁ = μ₂
• Critical points and tricritical points
• Gibbs phase rule: F = C - P + 2
• Applications: water, CO₂, mixtures

Chemical Equilibrium

• Chemical potential μ = (∂G/∂N) at constant T,P
• Equilibrium condition: Σᵢ νᵢμᵢ = 0
• Law of mass action
• Le Chatelier's principle
• Temperature dependence of K_eq
• Applications to reactions and ionization

Chemical Kinetics

• Rate laws: zeroth, first, second order
• Arrhenius equation: k = Ae^(-E_a/RT)
• Reaction mechanisms and intermediates
• Transition state theory (TST)
• Catalysis and enzyme kinetics
• Non-equilibrium processes

🔗 Bridge to Statistical Mechanics

After mastering classical thermodynamics, statistical mechanics reveals the microscopic originof thermodynamic laws:

S = k_B ln Ω
Boltzmann's entropy formula: Entropy is proportional to the logarithm of the number of microstates Ω. This is the bridge between thermodynamics (S) and statistical mechanics (Ω).
β = 1/k_BT
Temperature from statistics: Temperature emerges naturally as the parameter that determines the probability distribution over energy states: P(E) ∝ e^(-βE).
F = -k_BT ln Z
Free energy from partition function: All thermodynamic potentials can be derived from the partition function Z. Statistical mechanics provides a computational framework.

Study path: Thermodynamics gives you the phenomenology and experimental grounding. Statistical mechanics then explains why these laws hold and extends them to quantum systems, non-equilibrium processes, and microscopic calculations.

📺 Video Lecture Series

MIT 5.60 - Thermodynamics & Kinetics

36 comprehensive lectures from MIT's graduate thermodynamics course. Covers classical thermodynamics, phase equilibria, chemical thermodynamics, and chemical kinetics. Rigorous mathematical treatment with applications to chemistry and materials science.

Course structure:

• Lectures 1-12: Classical thermodynamics - laws, potentials, Maxwell relations
• Lectures 13-24: Phase equilibria and chemical thermodynamics
• Lectures 25-36: Chemical kinetics and reaction dynamics

Watch MIT 5.60 Lectures →

📚 Recommended Textbooks

H.B. Callen

Thermodynamics and an Introduction to Thermostatistics

The classic graduate text. Develops thermodynamics from postulational approach. Rigorous and elegant. Perfect companion to MIT 5.60.

E. Fermi

Thermodynamics

Concise and clear. Fermi's legendary clarity makes this a joy to read. Short but complete coverage of classical thermodynamics.

D.V. Schroeder

An Introduction to Thermal Physics

Excellent undergraduate text. Bridges thermodynamics and statistical mechanics early. Very accessible with great examples and problems.

P. Atkins

Physical Chemistry

For chemical applications and kinetics. Comprehensive coverage of thermodynamics, kinetics, and quantum chemistry. Standard chemistry text.

Prerequisites

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Calculus:
Multivariable calculus, partial derivatives, exact vs inexact differentials, Legendre transforms.
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Introductory Physics:
Basic thermodynamics (ideal gas, heat, work), energy conservation. This course goes much deeper.
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Chemistry (helpful):
Basic chemistry for chemical thermodynamics and kinetics sections. Not strictly required for classical thermodynamics.