• Who: Robert Boyle (1662) & later Edmé Mariotte (1679)
• What:
  • Pressure (P) of a fixed gas amount is inversely proportional to its volume (V) at constant temperature (T).
  • Algebraically: P∝\(\frac 1V\)​ or PV=constant (at constant T)
• Graphs:
  1. Pressure (P) vs Volume (V): Curved lines, different for each temperature (isothermals).
  2. Pressure (P) vs \(\frac 1V\)​: More useful for predictions.

Real-world example: Squeezing a balloon. As you decrease its volume (by squeezing), the pressure inside increases, making it harder to squeeze.

• Who: Jacques Charles (~1787) & announced by Joseph Gay-Lussac (1802)
• What:
  • Volume (V) of a fixed gas amount is directly proportional to the absolute temperature (T) at constant pressure (P).
  • Algebraically: V×T=constant (at constant P)
• Implication: If a gas's temperature drops to 0K (-273°C), its volume would be zero.

Real-world example: A helium balloon in cold weather. As the temperature drops, the balloon shrinks since its volume decreases with the temperature.

What:

• Pressure (P) of a fixed gas amount is directly proportional to the absolute temperature (T) at constant volume (V).
• Algebraically: P∝T or  P×T = constant (at constant V)

• Who: Count Amadeo Avogadro (1811)
• What:
  • Quantity of gas (n) is directly proportional to its volume (V) at constant temperature and pressure.
  • Algebraically: n∝V or ×V=constant (at constant T and P)

Real-world example: Think about different sized balloons. The larger the balloon, the more molecules (or air) it has inside it.