Key Concepts in Physical Chemistry and Thermodynamics and units

Kinetics

deals with the question of how fast a given process occurs

Thermodynamics

deals with the question of how much useful work can be produced by a given physical or chemical process - and, conversely, how much will necessarily be lost as heat

Statistical Mechanics

gives a microscopic interpretation to the macroscopic laws of thermodynamics and kinetics

Quantum Mechanics

is the physics of the very small - it lays out the fundamental laws that govern all systems at the microscopic level and, ultimately, give rise to the everything else

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Macroscopic quantity

Observable properties like pressure and volume.

Thermodynamic work

Energy transfer due to macroscopic displacement.

Microscopic quantities

Depend on individual particle coordinates and velocities.

Ideal gas

Gas with energy independent of temperature.

Hamiltonian

Total energy operator in quantum mechanics.

Adiabatic expansion

Process with no heat exchange with surroundings.

Entropy (∆S)

Measure of disorder or randomness in a system.

Carnot efficiency

Maximum efficiency of a heat engine between temperatures.

Heat of fusion

Energy needed to change solid to liquid at melting point.

Heat of vaporization

Energy required to convert liquid to gas at boiling point.

Phase transition

Change between solid, liquid, and gas states.

Reversible process

Process that can return to initial state without net change.

Isothermal process

Process occurring at constant temperature.

Isobaric process

Process occurring at constant pressure.

Thermodynamic energy (U)

Total internal energy of a system.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed.

Second Law of Thermodynamics

Entropy of an isolated system always increases.

Pressure-volume work

Work done by or on a gas during expansion.

SI unit of force

Newton, defined as kg·m/s².

SI unit of pressure

Pascal, defined as N/m².

SI unit of energy

Joule, defined as N·m or Pa·m³

Triple point

Condition where solid, liquid, and gas coexist.

Ideal gas law

PV=nRT, relates pressure, volume, and temperature.

Entropy change

Difference in entropy before and after a process.

Real gases

Gases that deviate from ideal behavior under certain conditions.

Absolute zero

Theoretical temperature where molecular motion stops.

Clausius statement

Heat cannot flow from cold to hot spontaneously.

Carnot's theorem

No engine can be more efficient than Carnot engine.

Coexistence of phases

Occurs at specific temperature and pressure conditions.

Thermal equilibrium

State where two bodies exchange no heat.