ME 340 Intermediate Thermodynamics - Class 3 Flashcards

Vocabulary flashcards covering core thermodynamics concepts, boundary types, thermodynamic processes, simple gas laws, and the four laws of thermodynamics from ME 340 Class 3 lecture notes.

State Postulate

The principle stating that the state of a simple compressible system (or pure substance) is completely specified by two independent, intensive properties such as $T$, $v$, $P$, $u$, $h$, or $s$.

State Function

A property such as internal energy ($U$), enthalpy ($H$), or entropy ($S$) that quantitatively describes the equilibrium state of a system regardless of the path or process used to reach that state.

Thermodynamic Process

Any change that a system undergoes from one thermodynamic state to another where observable properties change.

Thermodynamic Cycle

A sequence of thermodynamic processes undergoing changes of state where the initial and final end states are identical.

Control Mass

A closed system bounded by real surfaces where only energy in the form of heat and work can cross the system boundary, while mass remains trapped ($\Delta m = 0$).

Control Volume

An open system enclosed by a control surface through which mass, heat, and work can continuously flow into and out of the system.

Control Surface

The real or imaginary boundary that surrounds a control volume (open system).

Adiabatic Boundary

An insulated boundary that does not allow heat or mass to pass across it ($\Delta Q = 0$ and $\Delta m = 0$), permitting only energy transfer in the form of work.

Diathermic Boundary

A boundary that allows energy in the form of heat to pass across it by thermal conduction, but blocks work and mass transfer ($\Delta W = 0$ and $\Delta m = 0$).

Impermeable Boundary

A boundary that completely prevents the exchange of mass ($\Delta m = 0$) between a system and its surroundings.

Permeable Boundary

A boundary that allows mass exchange ($\Delta m \neq 0$) across it via diffusion regardless of species size or solubility.

Semipermeable Boundary

A boundary that selectively allows certain molecules or ions to pass through by diffusion while restricting others based on size, solubility, or chemical interaction.

Isentropic Process

An adiabatic, reversible process characterized by zero heat transfer ($dS = 0$), zero internal entropy generation ($S_{gen} = 0$), and zero overall entropy change ($\Delta S = 0$).

Isenthalpic Process

An adiabatic, irreversible process in which enthalpy remains constant ($\Delta h = 0$) and no work is extracted ($\Delta W = 0$).

Isochoric Process

A thermodynamic process occurring at constant volume ($\Delta V = 0$) in which no boundary $P\Delta V$ work is performed.

Isobaric Process

A thermodynamic process occurring at constant pressure ($\Delta P = 0$).

Isothermal Process

A thermodynamic process occurring at constant temperature ($\Delta T = 0$), where $PV = \text{constant}$ for an ideal gas.

Zeroth Law of Thermodynamics

The law stating that if two bodies are each in thermal equilibrium with a third body, they are in thermal equilibrium with each other, establishing temperature as a measurable quantity.

Isochoric Coefficient

The coefficient ($\alpha$) expressing the pressure increase of a material at fixed volume as a function of its volume and temperature.

Isobaric Volume Expansion Coefficient

The coefficient ($\beta$) expressing the volume expansion of a material at fixed pressure as a function of its temperature and pressure.

Isothermal Compressibility Coefficient

The coefficient ($\kappa$) expressing the compressibility of a material at fixed temperature as a function of its temperature and pressure.

Boyle's Law

A simple gas law stating that pressure is inversely proportional to volume ($P \propto \frac{1}{V}$ or $P_1 V_1 = P_2 V_2$) at constant temperature and moles.

Charles's Law

A simple gas law stating that volume is directly proportional to absolute temperature ($V \propto T$ or $\frac{V_1}{T_1} = \frac{V_2}{T_2}$) at constant pressure and moles.

Gay-Lussac's Law

A simple gas law stating that pressure is directly proportional to absolute temperature ($P \propto T$ or $\frac{P_1}{T_1} = \frac{P_2}{T_2}$) at constant volume and moles.

Avogadro's Law

A simple gas law stating that volume is directly proportional to the number of moles ($V \propto n$ or $\frac{n_1}{V_1} = \frac{n_2}{V_2}$) at constant temperature and pressure.

First Law of Thermodynamics

An expression of the conservation of energy principle asserting that energy cannot be created or destroyed, only transformed between forms ($\Delta U = Q - W$ for a stationary closed system).

Second Law of Thermodynamics

The law asserting that energy has quality as well as quantity, and natural processes occur in the direction of decreasing energy quality and increasing system entropy.

Third Law of Thermodynamics

A statistical law asserting that as a system approaches absolute zero, its entropy approaches a minimum value (zero for a perfect crystalline state).

Absolute Zero

The lowest possible theoretical temperature limit, defined as $0\,K$, $-273.15\,^\circ\text{C}$, or $-459.67\,^\circ\text{F}$, where system entropy reaches a minimum.