UNIT 1 KINETIC THEORY OF GASES

Kinetic Theory of Matter

• Introduction: The kinetic theory explains the behavior of matter, emphasizing the motion of particles.

States of Matter

• Categories: Solid, Liquid, Gas

Comparing States of Matter

Properties

Properties of Gas

• Four Properties: Pressure (P), Volume (V), Temperature (T), Amount (n)

  • Pressure (P): Force exerted by gas against walls (units: atm, mm Hg, torr, pascal)

  • Volume (V): Space occupied by gas (units: liter, milliliter)

  • Temperature (T): Affects kinetic energy (units: Celsius, Kelvin)

  • Amount (n): Quantity of gas (units: grams, moles)

Gas Laws

Boyle’s Law

• At constant temperature: P is inversely proportional to V.

• Equation: P1V1 = P2V2

Charles’ Law

• At constant pressure: V is directly proportional to T.

• Temperature must be in Kelvin.

• Equation: V1/T1 = V2/T2

Pressure Law

• At constant volume: P is directly proportional to T.

• Equation: P1/T1 = P2/T2

Ideal Gas Equation

• Formula: PV = nRT

  • P = pressure (Pa), V = volume (m³), n = moles, R = gas constant, T = temperature (K)

Properties of Liquid

• Key Features:

  1. Viscosity: Resistance to flow; affected by intermolecular forces and temperature.

  2. Capillary Action: Spontaneous rise or fall in narrow tubes; affected by surface interactions.

  3. Surface Tension: Resistance of the liquid's surface due to molecular cohesion.

  4. Incompressibility: Little volume change under pressure.

  5. Fluidity: Ability to flow, inversely related to viscosity.

  6. Density: Defined volume; liquids are denser than gases but less dense than solids.

  7. Vapor Pressure: Pressure exerted by vapor above a liquid at equilibrium.

  8. Diffusion: Mixing of liquids occurs to some degree.

  9. Boiling/Freezing Points: Defined transition temperatures for phase changes.

  10. Solubility: Ability of liquids to dissolve solutes.

  11. Expansion/Contraction: Volume change with temperature change.

Phase

• Definition: A uniform region of material with specific properties; phase transitions occur with changes in temperature or pressure.

Real vs. Ideal Gas

Ideal Gas

• Definition: A hypothetical gas that perfectly follows gas laws.

• Assumptions:

  • Particles have no volume.

  • No intermolecular forces.

  • All collisions are elastic.

  • Kinetic energy is proportional to temperature in Kelvin.

• Behavior: Described accurately by the ideal gas law (PV = nRT).

Real Gas

• Definition: A gas that deviates from ideal behavior due to particle interactions and volume.

• Conditions Affecting Behavior:

  • High Pressure: Significant particle volume affects behavior.

  • Low Temperature: Intermolecular forces impact behavior.

• Behavior: May condense and described by equations like the Van der Waals equation.

Key Differences