Modelling a gas

Understandings:

• Molecular theory of solids, liquids and gases
• Temperature and absolute temperature
• Internal energy
• Pressure
• Equation of state for an ideal gas
• Kinetic model of an ideal gas
• Mole, molar mass and the Avogadro constant
• Differences between real and ideal gases

Applications and skills:

• Describing temperature change in terms of internal energy
• Using Kelvin and Celsius temperature scales and converting between them
• Solving problems using the equation of state for an ideal gas and gas laws
• Sketching and interpreting changes of state of an ideal gas on pressure–volume, pressure–temperature and volume–temperature diagrams
• Investigating at least one gas law experimentally

Guidance:

• Internal energy is taken to be the total intermolecular potential energy + the total random kinetic energy of the molecules
• Students should be aware of the assumptions that underpin the molecular kinetic theory of ideal gases
• Gas laws are limited to constant volume, constant temperature, constant pressure and the ideal gas law
• Students should understand that a real gas approximates to an ideal gas at conditions of low pressure, moderate temperature and low density