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AP® Chemistry · Unit 3 · Topic 3.5

Kinetic Molecular Theory: Topic Checklist (Chemistry 3.5)

Specific “I can…” statements for the kinetic molecular theory, each linked to the guide section and practice question that shows whether you can really do it.

Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.

Understanding

  • I can state the five assumptions of the kinetic molecular theory for an ideal gas. (Guide: “The assumptions of the model”)
  • I can explain that all particles of matter, not only gas particles, are in continuous random motion. (Guide: “From a law to a model”)
  • I can explain gas pressure as the force of particle–wall collisions per unit area. (Guide: “Pressure from collisions”; Practice Q1)
  • I can state that the average kinetic energy of the particles is proportional to the Kelvin temperature, and that it is the same for every gas at the same temperature. (Guide; Practice Q5(b))

Calculation

  • I can use KE = ½mv² to find the ratio of the average speeds of two gases at the same temperature. (Guide: Worked example 1; Practice Q3, Q7(a))
  • I can find the factor by which the average kinetic energy and the average speed change when a gas is heated, using kelvin. (Guide: Worked example 2; Practice Q4, Q6(b))
  • I can combine KMT with PV = nRT to find a new pressure after heating. (Practice Q6(a))

Reasoning

  • I can explain, with two separate effects on collisions, why heating a gas at constant volume raises its pressure. (Guide: Worked example 2; Practice Q6(c))
  • I can explain why compressing a gas at constant temperature raises the pressure without changing the average speed. (Guide: “Pressure from collisions”)
  • I can draw particle diagrams of a gas at two temperatures with the right features kept the same and changed. (Guide: Figure 1; Practice Q6(d))
  • I can sketch and describe how a Maxwell–Boltzmann distribution changes with temperature, keeping the area constant. (Guide: Figure 2; Practice Q2)
  • I can identify which speed distribution belongs to the lighter gas, and explain why kinetic-energy distributions at the same temperature are identical. (Guide: Figure 3; Practice Q5, Q7(c))
  • I can evaluate a claim about partial pressures in a gas mixture using KMT. (Practice Q7(b))

All ticked? Move on to Topic 3.6, Deviation from Ideal Gas Law, or return to the course roadmap.

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