Lecture on Gas Laws

Introduction

• Gas laws individually aren't very important.
• Extra information included for explanation.
• Focus on the relationships between variables: pressure, temperature, volume, and number of moles.
• Ideal Gas Law will be covered in the next lecture.

Individual Gas Laws

• Boyle’s Law

  • Relationship: Pressure vs. Volume
  • Inverse proportionality
  • At constant temperature and moles, Pressure x Volume = constant
  • Graph: Inverse curve becomes a straight line when plotting Pressure vs. 1/Volume.

• Amontons' Law (or Gay-Lussac's Law)

  • Relationship: Pressure vs. Temperature
  • Direct proportionality
  • At constant volume and moles, Pressure/Temperature = constant
  • Connection to Kelvin scale: Absolute zero at -273.15°C (0 Kelvin)
  • Explanation of absolute zero: No molecular motion, hence no pressure.

• Charles’ Law

  • Relationship: Volume vs. Temperature
  • Direct proportionality
  • At constant pressure and moles, Volume/Temperature = constant
  • Graphs all converge at absolute zero (-273.15°C).

• Avogadro’s Law

  • Relationship: Pressure vs. Number of Moles
  • Direct proportionality
  • At constant temperature and volume, Pressure/Number of Moles = constant

Important Concepts

• Absolute zero: Absence of energy and molecular motion.
• Kelvin scale: Starts at absolute zero with the same size degrees as Celsius.

Conclusion

• No need to memorize individual gas laws.
• All relationships are encapsulated in the Ideal Gas Law.