Physical Transformations of Pure Substances

This set of flashcards covers key concepts related to the physical transformations of pure substances, focusing on phases, phase diagrams, phase transitions, and thermodynamic stability.

Phase

A form of matter that has uniform chemical composition in the same physical state.

Single Phase Systems

Systems that contain only one phase, such as pure gases, liquids, or solids.

Multiple Phase Systems

Systems that consist of multiple phases, such as ice-water slurries or liquid in equilibrium with its vapor.

Phase Transition

The spontaneous conversion of one phase into another phase at a given temperature and pressure.

Transition Temperature

The temperature at which two phases are in equilibrium at a specified pressure.

Metastable Phase

A thermodynamically unstable phase where the transition is kinetically hindered.

Chemical Potential (μ)

The change in the free energy of a system when an additional particle is introduced, equal to Gm for a one-component system.

Phase Diagram

A graphical representation of the phases that are thermodynamically stable over a range of temperatures and pressures.

Vapor Pressure

The pressure of vapor in equilibrium with its liquid phase.

Triple Point

The unique set of conditions at which three different phases coexist in thermodynamic equilibrium.

Degrees of Freedom (F)

The number of independent parameters that can be varied without changing the number of phases in equilibrium.

Critical Point

The point at which the density of the vapor and liquid are equal and the phase boundary disappears.

Phase Rule

A formula that relates the number of phases, components, and degrees of freedom in a system, F = C - P + 2.

Standard Boiling Point

The temperature at which boiling occurs at a pressure of 1 bar.

Supercritical Fluid

A state of matter occurring above the critical temperature and critical pressure.

Phase

A form of matter that has uniform chemical composition in the same physical state.

Single Phase Systems

Systems that contain only one phase, such as pure gases, liquids, or solids.

Multiple Phase Systems

Systems that consist of multiple phases, such as ice-water slurries or liquid in equilibrium with its vapor.

Phase Transition

The spontaneous conversion of one phase into another phase at a given temperature and pressure.

Transition Temperature

The temperature at which two phases are in equilibrium at a specified pressure.

Metastable Phase

A thermodynamically unstable phase where the transition is kinetically hindered.

Chemical Potential (\mu)

The change in the free energy of a system when an additional particle is introduced, equal to G_m for a one-component system.

Phase Diagram

A graphical representation of the phases that are thermodynamically stable over a range of temperatures and pressures.

Vapor Pressure

The pressure of vapor in equilibrium with its liquid phase.

Triple Point

The unique set of conditions at which three different phases coexist in thermodynamic equilibrium.

Degrees of Freedom (F)

The number of independent parameters that can be varied without changing the number of phases in equilibrium.

Critical Point

The point at which the density of the vapor and liquid are equal and the phase boundary disappears.

Phase Rule

A formula that relates the number of phases, components, and degrees of freedom in a system, F = C - P + 2.

Standard Boiling Point

The temperature at which boiling occurs at a pressure of 1 bar.

Supercritical Fluid

A state of matter occurring above the critical temperature and critical pressure.

Melting Point

The temperature at which a solid converts into a liquid at a given pressure.

Sublimation

The direct transition of a substance from the solid to the gas phase without passing through the liquid phase.

Phase Boundary

A line on a phase diagram that separates thermodynamically stable phases.

Gibbs Free Energy (G)

A thermodynamic potential that measures the useful or process-initiating work obtainable from an isothermal, isobaric thermodynamic system.

Normal Boiling Point

The temperature at which the vapor pressure of a liquid equals the standard atmospheric pressure (1 atm).