Particle Model & Thermodynamics – Vocabulary Flashcards

A set of vocabulary flashcards summarising key terms, definitions, and equations from the lecture notes on density, changes of state, internal energy, specific heat capacity, specific latent heat, and gas pressure relationships.

Density (ρ)

The mass per unit volume of a substance, measured in kilograms per cubic metre (kg/m³).

Density Formula

ρ = m ⁄ V, where m is mass (kg) and V is volume (m³).

Mass Conservation in State Changes

The total mass of a substance remains constant when it melts, boils, condenses, etc.

Melting

The physical change from solid to liquid.

Evaporating

The physical change from liquid to gas.

Condensing

The physical change from gas to liquid.

Freezing

The physical change from liquid to solid.

Sublimation

The direct change of a solid into a gas without passing through the liquid state.

Internal Energy

The total kinetic and potential energy stored by the particles of a system.

Kinetic Energy (of particles)

Energy due to the motion or vibration of particles; increases with temperature.

Potential Energy (of particles)

Energy stored because of the positions and spacing between particles.

Specific Heat Capacity (c)

The energy required to raise the temperature of 1 kg of a substance by 1 °C, in J kg⁻¹ °C⁻¹.

Specific Heat Capacity Formula

ΔE = m c ΔT, where ΔE is energy (J), m is mass (kg), c is SHC (J kg⁻¹ °C⁻¹) and ΔT is temperature change (°C).

Specific Latent Heat (L)

Energy needed to change the state of 1 kg of a substance at constant temperature, in J kg⁻¹.

Latent Heat of Fusion

Specific latent heat associated with melting or freezing.

Latent Heat of Vaporisation

Specific latent heat associated with boiling or condensing.

Specific Latent Heat Formula

E = m L, where E is energy (J), m is mass (kg) and L is specific latent heat (J kg⁻¹).

Heating Curve Flat Sections

Horizontal parts of a temperature-time graph where added energy changes state but temperature stays constant.

Gas Pressure

The force per unit area exerted by gas particles colliding with the walls of their container.

Boyle’s Law

For a fixed mass of gas at constant temperature, pressure and volume are inversely proportional.

Boyle’s Law Formula

P₁ V₁ = constant (or P V = constant).

Work Done on a Gas

Energy transferred to a gas when it is compressed, increasing internal energy and temperature.

Work Done Formula

W = p ΔV (or W = p V for a constant-pressure process), where p is pressure and V is volume.

Temperature–Particle Speed Relationship

In a gas, higher temperature means higher average kinetic energy, so particles move faster.