Lecture 1: Introduction to Thermodynamics

Vocabulary flashcards covering core concepts, systems, processes, laws of thermodynamics, and ideal gas equations from Lecture 1 (5.601).

Thermodynamics

The branch of physical science that describes the macroscopic properties of equilibrium systems, built entirely on four empirical laws and simple mathematics.

Zeroth Law of Thermodynamics

States that if System A and System B are in thermal equilibrium, and System B and System C are in thermal equilibrium, then System A and System C are also in thermal equilibrium. This law defines temperature ($T$).

First Law of Thermodynamics

The fundamental thermodynamic law that defines internal energy ($U$).

Second Law of Thermodynamics

The fundamental thermodynamic law that defines entropy ($S$).

Third Law of Thermodynamics

The fundamental thermodynamic law that assigns a numerical value to entropy.

System

The specific part of the Universe that is chosen to be studied.

Surroundings

The rest of the Universe outside of the defined system.

Boundary

The real or imaginary surface dividing the System from the Surroundings.

Open System

A system that can transfer both mass and energy between the System and the Surroundings.

Closed System

A system that can transfer energy between the System and the Surroundings, but cannot transfer mass.

Isolated System

A system in which neither mass nor energy can transfer between the System and the Surroundings.

Extensive Property

A thermodynamic property that depends directly on the size or quantity of the system, such as mole number ($n$), mass ($m$), or volume ($V$).

Intensive Property

A thermodynamic property that is independent of the size of the system, such as temperature ($T$), pressure ($p$), or molar volume ($\bar{V} = \frac{V}{n}$).

State of a System

The equilibrium condition defined by the collection of all macroscopic properties described by state variables ($p$, $n$, $T$, $V$), which is independent of the system's history.

Path

The sequence of intermediate states passed through during a change of state.

Reversible Process

A process that follows a path where the system remains in thermodynamic equilibrium at all times.

Irreversible Process

A process that does not maintain equilibrium throughout its path and defines the direction of time.

Adiabatic Process

A process in which no heat transfer occurs between the system and its surroundings.

Isobaric Process

A thermodynamic process that takes place at constant pressure.

Isothermal Process

A thermodynamic process that takes place at constant temperature.

Thermal Equilibrium

The state reached when heat flow stops between objects in thermal contact, resulting in both bodies having the same temperature.

Absolute Zero

The temperature at which $t = -273.15\,^\circ\text{C}$ ($T = 0\,\text{K}$), serving as the foundational zero point of the absolute temperature scale.

Kelvin Scale

An absolute temperature scale defined by the equation $T(\text{K}) = t(^\circ\text{C}) + 273.15$.

Triple Point of Water

A fundamental thermodynamic reference point set at $T_{tp} = 273.16\,\text{K}$.

Gas Constant ($R$)

The universal constant defined as $R = \frac{\lim_{p \rightarrow 0}(p\bar{V})_{tp}}{273.16} = 8.31451\,\text{J\,K}^{-1}\text{mol}^{-1}$.

Ideal Gas Law

The equation of state $p\bar{V} = RT$ (or $pV = nRT$), valid for ideal gases at all pressures because the gas molecules do not interact.

Equation of State

A functional relationship among state variables that describes a system at equilibrium, such as $V = f(n, p, T)$ or $p = g(n, V, T)$.