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Physics SL

SLHL

Chapter 9: The Gas Laws

Build gas-law fluency from mole counting and pressure origins to $PV = nRT$, Boltzmann scaling, and the limits of ideal-gas assumptions.

Estimated chapter time: 165 minutes

IB syllabus: B.3 · SL and HL

Chapter Topics

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  1. 1How to Read This Gas Laws Chapter
    1. 1.1Why Gases Need a Dual Lens
    2. 1.2Absolute Temperature and Model Boundaries
    3. 1.3How This Chapter Is Structured
  2. 29.1 Moles, Molar Mass, and the Avogadro Constant
    1. 2.1Amount of Substance as a Counting Bridge
    2. 2.2Molar Mass and Mass-to-Mole Conversion
    3. 2.3Particle Count in Macroscopic Samples
  3. 39.2 Pressure and the Ideal-Gas Model
    1. 3.1Pressure as Momentum Transfer per Unit Area
    2. 3.2Molecular Collisions and Normal Momentum Change
    3. 3.3Ideal-Gas Assumptions and Their Meaning
    4. 3.4When Real Gases Behave Approximately Ideally
  4. 49.3 Equation of State and Gas Transformations
    1. 4.1From Empirical Laws to a Single Unified Law
    2. 4.2Equation of State in Mole and Particle Form
    3. 4.3Process Maps and Multi-Step Problem Solving
  5. 59.4 Boltzmann Equation, RMS Speed, and Internal Energy
    1. 5.1From Speed Distribution to RMS Speed
    2. 5.2Pressure-Density-RMS Relation
    3. 5.3Microscopic Kinetic Energy and Internal Energy
  6. 69.5 Real Gases and Model Limitations
    1. 6.1Where the Ideal Model Starts to Fail
    2. 6.2Finite Molecular Volume and Intermolecular Forces
    3. 6.3Compressibility Factor as a Deviation Signal
  7. 7Chapter 9 Wrap-Up
    1. 7.1A Repeatable Workflow for Gas-Law Problems

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