9478 / 2027

Chapter 12

Temperature and Ideal Gases

Name the particles, use kelvin and absolute pressure, and distinguish a gas measurement from the assumptions used to explain it.

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  1. Temperature on an absolute scale

    Convert Celsius and kelvin readings and distinguish a temperature, an interval and an absolute-temperature ratio.

  2. Particles, moles and mass

    Name the entities being counted and connect sample mass, amount of substance and particle number.

  3. Use the ideal-gas equation

    Calculate gas states, compare controlled changes and interpret a fixed-volume pressure-temperature investigation.

  4. Pressure from particle collisions

    Derive pressure from wall impulses, same-wall return times and isotropic mean-square velocity components.

  5. Temperature and particle energy

    Relate absolute temperature to mean translational kinetic energy and compare mean and rms speeds.

Syllabus coverage

This chapter covers Temperature and Ideal Gases, topic 12(a-g), in the 9478 syllabus (2027).

Connect measurable gas quantities with a microscopic model while keeping counts, averages and controlled conditions clear.

Thermodynamic temperature, moles and particle number, the ideal-gas equation, kinetic-theory assumptions and pressure derivation, mean translational energy and rms speed.

View the learning outcomes
12(a)
Explain an absolute thermodynamic temperature scale independent of a particular substance's property. Temperature on an absolute scale
12(b)
Convert between Celsius and thermodynamic temperatures using the 273.15 offset. Temperature on an absolute scale
12(c)
Recall and use pV = NkT, with N the specified particle number. Use the ideal-gas equation
12(d)
State the mole in terms of particle number, use the Avogadro constant and N = nN_A, and establish Nk = nR. Particles, moles and massUse the ideal-gas equation
12(e)
State the basic assumptions of the kinetic theory of an ideal gas. Pressure from particle collisions
12(f)
Explain pressure through random particle motion and derive pV = Nm mean(c^2)/3 from wall impulses and three-dimensional averaging. Pressure from particle collisions
12(g)
Recall and apply mean translational kinetic energy = m mean(c^2)/2 = 3kT/2. Temperature and particle energy