Lesson 07
Test
Assess understanding of temperature, gases, and thermodynamics.
Syllabus
CIE 9702 syllabus points
21 linked
- 14.1.1 understand that (thermal) energy is transferred from a region of higher temperature to a region of lower temperature
- 14.1.2 understand that regions of equal temperature are in thermal equilibrium
- 14.2.1 understand that a physical property that varies with temperature may be used for the measurement of temperature and state examples of such properties, including the density of a liquid, volume of a gas at constant pressure, resistance of a metal, e.m.f. of a thermocouple
- 14.2.2 understand that the scale of thermodynamic temperature does not depend on the property of any particular substance
- 14.2.3 convert temperatures between kelvin and degrees Celsius and recall that T / K = θ / °C + 273.15
- 14.2.4 understand that the lowest possible temperature is zero kelvin on the thermodynamic temperature scale and that this is known as absolute zero
- 14.3.1 define and use specific heat capacity
- 14.3.2 define and use specific latent heat and distinguish between specific latent heat of fusion and specific latent heat of vaporisation
- 15.1.1 understand that amount of substance is an SI base quantity with the base unit mol
- 15.1.2 use molar quantities where one mole of any substance is the amount containing a number of particles of that substance equal to the Avogadro constant NA
- 15.2.1 understand that a gas obeying pV ∝ T, where T is the thermodynamic temperature, is known as an ideal gas
- 15.2.2 recall and use the equation of state for an ideal gas expressed as pV = nRT, where n = amount of substance (number of moles) and as pV = NkT, where N = number of molecules
- 15.2.3 recall that the Boltzmann constant k is given by k = R / NA
- 15.3.1 state the basic assumptions of the kinetic theory of gases
- 15.3.2 explain how molecular movement causes the pressure exerted by a gas and derive and use the 1 1
- 15.3.3 understand that the root-mean-square speed cr.m.s. is given by <c 2 > 1
- 15.3.4 compare pV = 3 Nm<c2> with pV = NkT to deduce that the average translational kinetic energy of a 3
- 16.1.1 understand that internal energy is determined by the state of the system and that it can be expressed as the sum of a random distribution of kinetic and potential energies associated with the molecules of a system
- 16.1.2 relate a rise in temperature of an object to an increase in its internal energy
- 16.2.1 recall and use W = p∆V for the work done when the volume of a gas changes at constant pressure and understand the difference between the work done by the gas and the work done on the gas
- 16.2.2 recall and use the first law of thermodynamics ∆U = q + W expressed in terms of the increase in internal energy, the heating of the system (energy transferred to the system by heating) and the work done on the system
Definitions
Required definitions
Specific heat capacity
the energy required per unit mass per unit temperature rise.
Specific latent heat
the energy required per unit mass to change state without a change in temperature.
Specific latent heat of fusion
the energy required per unit mass to change between solid and liquid without a change in temperature.
Specific latent heat of vaporisation
the energy required per unit mass to change between liquid and gas without a change in temperature.
Lesson Notes
Student guidance and lesson notes
Overview
This test checks the full A2 thermal physics topic: temperature, specific heat capacity, latent heat, ideal gases, kinetic theory, internal energy, and the first law of thermodynamics.
What You Need to Know
- Show your working clearly when choosing between thermal energy, ideal gas, kinetic theory, and thermodynamics equations.
- Use kelvin temperatures and SI units throughout gas calculations.
- Define symbols before using equations with similar-looking quantities.
- Explain physical models in words when the question asks for assumptions or mechanisms.
How to Work Through It
- Read each question carefully and identify the physical process being modelled.
- Write down known quantities, convert units, and choose the relevant equation.
- Keep signs explicit in first-law questions.
- Check final answers for units, significant figures, and physical sense.
Check Your Understanding
- Can you explain why kelvin is required for gas equations?
- Can you distinguish moles, molecules, molecule mass, and total gas mass?
- Can you account for energy transfer using delta U = q + W?
Common Mistakes
- Using the right equation with the wrong units.
- Choosing a thermal energy equation from keywords rather than from the physical process.
- Giving vague kinetic theory explanations that miss momentum change at the container wall.
- Losing first-law marks through unclear sign conventions.
Next Steps
- Use the review lesson to correct mistakes and identify which thermal physics skills need more practice.
- Keep working visible so feedback can target the exact weak step.