Concise Notes on Solids, Liquids, Gases, Kinetic Theory, and Diffusion

Kinetic Theory

• Explains the physical properties of solids, liquids, and gases based on particle arrangement and motion.

States of Matter

• Solid: Fixed volume and shape, high density, particles in fixed, regular pattern, vibrate in position.

• Liquid: Fixed volume, adopts container shape, less dense than solids (usually), particles move and slide.

• Gas: No fixed volume, adopts container shape, very low density, compressible, particles move randomly and quickly.

State Changes

• Involve changes in energy, arrangement, and particle movement.

• Melting: Solid to liquid, requires heat, occurs at melting point.

• Freezing: Liquid to solid, requires heat loss, occurs at freezing point (same as melting point).

• Boiling: Liquid to gas, requires heat, occurs at boiling point.

• Evaporation: Liquid to gas, occurs at surface over a range of temperatures.

• Condensation: Gas to liquid, occurs on cooling over a range of temperatures.

• Heating solids increases particle vibration until melting occurs.

• Heating liquids increases particle movement until evaporation/boiling occurs.

• Cooling a gas has the reverse effect.

• Heating/cooling curves show temperature changes during state transitions; horizontal sections indicate state changes at constant temperature.

Pressure & Temperature in Gases

• Gas volume increases with temperature; density decreases.

• Pressure increases as volume decreases.

• Gas pressure is from particles hitting container walls.

• Increased temperature increases particle kinetic energy and collision frequency.

• Increased pressure decreases volume, increasing collision frequency.

Diffusion Concepts

• Diffusion: Particles move from high to low concentration areas.

• Occurs in gases and liquids due to random particle motion; faster at higher temperatures.

• Gases diffuse faster than liquids due to higher particle energy.

• Lighter gases (lower molecular mass) diffuse faster and travel further.

• Heavier gases (higher molecular mass) diffuse slower and travel less far.