SCI10 Q4 MOD1.3

Kinetic Molecular Theory of Gases

Properties of Matter

• Definition: Matter has mass and volume.

• Observable Properties: Hardness, texture, color, flexibility, malleability, electrical conductivity:

  • Solids & Liquids: These properties are easily studied.

  • Gases: Properties are not directly measurable; behavior is explained through Kinetic Molecular Theory (KMT).

States of Matter

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  • Solid: Particles are very close and move in fixed positions (strong attractions).

  • Liquid: Particles are far apart and can slide against each other (weaker attractions).

  • Gas: Particles are far apart with very weak forces of attraction and have no definite shape or volume (freely moving).

Key Differences in Properties of States

Kinetic Molecular Theory (KMT) Overview

• Explains properties and behavior of gases:

  • Expresses relationships among pressure, volume, and temperature at a molecular level.

  • Discusses behavior of atoms and molecules making up gases.

General Observations About Gases

• Gases: occupy a small space, can spread, are composed of tiny particles in constant motion.

• Increase in temperature causes gas particles to move and spread faster.

The KMT Postulates

1. Large Number of Particles: Gases consist of a vast number of particles that are very small compared to the distance between them.

2. Random Motion and Collision: Gas particles move randomly and collide with each other and their container, creating pressure.

3. Elastic Collisions: Collisions between gas molecules are perfectly elastic, meaning no energy is lost.

4. Negligible Interactions: Gas particles experience negligible attractions and repulsions.

5. Kinetic Energy and Temperature: Average kinetic energy of gas particles is directly proportional to their temperature (Kelvin).