This lesson explores how matter behaves in different physical states, the kinetic particle theory, and how macroscopic properties arise from microscopic particle motion.

1. Core Concepts (Short Notes)

6.1 States of Matter

Matter exists mainly in three states:

• Solid: Fixed shape and volume; particles vibrate closely in fixed positions.

• Liquid: Fixed volume but no fixed shape; particles are close but free to move.

• Gas: No fixed shape or volume; particles are far apart and move rapidly.

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6.2 Kinetic Particle Theory

All matter consists of particles in constant motion.

• Higher temperature → faster particle motion.

• Solids have the least kinetic energy; gases have the most.

  
  

6.3 Intermolecular Forces

Strength of attraction between particles:

• Strongest in solids.

• Moderate in liquids.

• Weakest in gases.

These forces determine melting and boiling points.

6.4 Gas Laws

The behavior of gases can be described using:

Boyle’s Law

P ∝ 1/V (constant temperature)

Charles’ Law

V ∝ T (constant pressure)

Combined Gas Law

(P₁V₁)/T₁ = (P₂V₂)/T₂

6.5 Ideal Gas Equation

PV = nRT Where:

• P = pressure (Pa)

• V = volume (m³)

• n = moles

• R = gas constant (8.314 J/mol·K)

• T = temperature (K)

  
  

6.6 Kinetic Theory of Gases

• Gas particles move randomly at high speeds.

• Collisions are elastic.

• Pressure is caused by collisions with container walls.

  
  

6.7 Real vs. Ideal Gases

Real gases deviate from ideal behavior at:

• High pressure

• Low temperature

Van der Waals equation corrects deviations: (P + a(n/V)²)(V – nb) = nRT

2. Key Formulas to Memorize

• Boyle’s Law: P₁V₁ = P₂V₂

• Charles’ Law: V₁/T₁ = V₂/T₂

• Combined Gas Law: (P₁V₁)/T₁ = (P₂V₂)/T₂

• Ideal Gas: PV = nRT

Conversions:

• Temperature must be in Kelvin.

• 1 atm = 101,325 Pa

3. Tips & Tricks for Exams

• Convert °C → K by adding 273.

• If pressure increases, volume decreases (Boyle’s Law).

• Keep units consistent: Pa, m³, K.

• Use the ideal gas equation for molar mass calculations.

• At RTP, use 24 dm³ per mole only for simple gas questions.

• For combined gas law problems, label each value clearly.

• Real gases behave ideally at high temperature and low pressure.

4. Important Points to Remember

• Solids have strong forces; gases have weak forces.

• Temperature affects the kinetic energy of particles.

• Gas laws describe relationships between P, V, and T.

• Ideal gas equation is a powerful tool for many calculations.

Real gases deviate from ideal behavior under extreme conditions.