Week 4: Pure Substances, Ideal Gas Equation Introduction

Pure Substance

A substance with a fixed chemical composition throughout, examples include single chemical elements like Nitrogen, compounds like Water, and mixtures like Air.

Phases of a Pure Substance

Identified by distinct molecular arrangements that are homogeneous throughout, including Solid, Liquid, and Gas phases with specific molecular behaviors.

Phase-Change Processes of Pure Substances

Describes energy changes during processes like Solid to Liquid and Liquid to Gas, involving sensible and latent internal energy changes.

Energy Changes During Phase Change Processes

Heating a substance increases sensible internal energy (U), while melting or vaporizing increases latent internal energy with specific heat capacities and latent heats.

Property Diagrams for Phase Change Processes

Include 𝑇−𝑣 and 𝑃−𝑣 diagrams showing critical points, saturation lines, regions, and constant pressure or temperature lines for substances undergoing phase changes.

Ideal Gas Equation of State

Described by 𝑃𝑉 = 𝑚𝑅𝑇, where 𝑅 is the specific gas constant, applicable to gases with low density under certain assumptions.