Properties of Pure Substances

These flashcards include key vocabulary and definitions related to the properties of pure substances, specifically focusing on phases, phase changes, and related thermodynamic concepts.

Pure Substance

A material with a uniform and invariable chemical composition that can exist in one or more phases.

Homogeneous Composition

A key characteristic of a pure substance where the composition is uniform throughout.

Phases of Matter

The three primary phases are solid, liquid, and gas/vapor.

Triple Point

The unique condition where all three phases (solid, liquid, gas) coexist in equilibrium.

Critical Point

The state beyond which the liquid and gas phases become indistinguishable.

Saturated Liquid

Water at its boiling point but still in liquid form.

Saturated Vapor

Steam at the boiling point with no liquid present.

Wet Steam

A mixture of saturated liquid and saturated vapor.

Dry Steam

Steam with no liquid droplets present.

Superheated Steam

Steam heated above its saturation temperature.

Enthalpy (h)

Total heat content, measured in kJ/kg.

Entropy (s)

Measure of disorder, expressed in kJ/kg·K.

Temperature-Enthalpy (T-h) Diagram

A graphical representation plotting temperature against enthalpy to visualize heat addition during phase changes.

Quality of Steam

Indicates the ratio of the mass of vapor to the total mass in wet steam.

Latent Heat (h_fg)

Energy required for phase change without temperature change.

Power Plants (Rankine Cycle)

Uses steam turbines which operate using superheated steam.

Mollier Diagram

Plots enthalpy against entropy and is used for analyzing steam turbines and compressors.

Saturation Temperature

The boiling point at a given pressure.