gas laws

• Today's discussion will be talking about the behavior of gases particularly about Boyle's law and Charles law
• States of matter


  • Solids
  • Liquids
  • Gases
• Properties of gases


  • Pressure (P)
  • Volume (V)
  • Temperature (T)
  • Amount (n)
• Pressure


  Force acting on a specific area
• Units of pressure


  • atm (atmosphere)
  • mmHg (millimeter mercury)
  • Torr
  • psi (pounds per square inch)
  • kPa (kilopascals)
• Volume


  Three-dimensional space occupied by a gas
• Units of volume


  • milliliters
  • liters
  • cubic meters
  • cubic centimeters
• Temperature


  Measure of the average kinetic energy of the particles in an object
• Units of temperature


  • Fahrenheit
  • Celsius
  • Kelvin
• Quantity


  Measured in moles
• Boyle's law relates pressure and volume at constant temperature and amount of substance
• Boyle's law


  Pressure is inversely proportional to the volume at constant temperature
• Demonstration of Boyle's law

  1. Put marshmallow in syringe

  2. Observe what happens when volume decreases and pressure increases

  3. Observe what happens when volume increases and pressure decreases
• If pressure doubles, volume should reduce to half. If pressure quadruples, volume should be one-fourth of the original.
• Applications of Boyle's law

  • Action of a syringe
  • Chips bag at higher altitude
  • Breathing (diaphragm movement)
• Charles law relates volume and temperature at constant pressure
• Charles law


  Volume and temperature are directly proportional
• Applications of Charles law

  • Hot air balloon
  • Ping pong balls
  • Baking (bread, pastries)
• Gay Lussac's Law


  Relates pressure and temperature
• Pressure and temperature


  Directly proportional if volume and amount of substance are constant
• Formula for Gay Lussac's Law

  p1/t1 = p2/t2
• Pressure must be expressed in pressure units (e.g. atmospheres, torr, mm Hg, kPa)
• Temperature must be in Kelvin
• To convert from Celsius to Kelvin, add 273
• Solving Gay Lussac's Law problems


  1. Identify given information (p1, t1, p2 or t2)

  2. Rearrange equation to solve for unknown (t2 or p2)

  3. Substitute values and calculate