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Gas Laws Overview

Sep 14, 2025

Overview

This lecture introduces three fundamental gas laws—Boyle's Law, Charles's Law, and Gay-Lussac's Law—comparing their relationships among pressure, volume, and temperature.

Boyle's Law

  • The mass of gas is constant in Boyle's Law.
  • Pressure and volume are inversely proportional: as pressure increases, volume decreases, and vice versa.
  • Density and pressure are directly proportional: as pressure rises, density increases.
  • Key formula: ( P_1V_1 = P_2V_2 ) or ( \frac{P_1}{V_1} = \frac{P_2}{V_2} ).
  • Pressure (P) times volume (V) equals a constant (K).

Charles's Law

  • Pressure is constant in Charles's Law.
  • Temperature and volume are directly proportional: as temperature increases, volume increases.
  • Density is inversely proportional to temperature: as temperature increases, density decreases.
  • Key formula: ( \frac{V_1}{T_1} = \frac{V_2}{T_2} ).
  • Volume (V) divided by temperature (T) equals a constant (K).

Gay-Lussac's Law

  • Mass is fixed and volume is constant in Gay-Lussac's Law.
  • Pressure and temperature are directly proportional: as temperature increases, pressure increases.
  • Key formula: ( \frac{P_1}{T_1} = \frac{P_2}{T_2} ).

Key Terms & Definitions

  • Pressure (P) — The force exerted by gas particles per unit area.
  • Volume (V) — The amount of space the gas occupies.
  • Temperature (T) — A measure of the average kinetic energy of gas particles.
  • Density — Mass per unit volume of a substance.
  • Proportionality Constant (K) — A constant value representing the relationship between variables in each gas law.

Action Items / Next Steps

  • Review the formulas for all three gas laws.
  • Practice applying each law to sample problems involving gas pressure, volume, and temperature.