• Reactants can be either limiting or excess.

• The experimental yield can be different from the theoretical yield.

• Avogadro’s law enables the mole ratio of reacting gases to be determined from volumes of the gases.

• The molar volume of an ideal gas is a constant at specified temperature and pressure.

• The molar concentration of a solution is determined by the amount of solute and the volume of solution.

• A standard solution is one of known concentration.

• Solution of problems relating to reacting quantities, limiting and excess reactants, theoretical, experimental and percentage yields.

• Calculation of reacting volumes of gases using Avogadro’s law.

• Solution of problems and analysis of graphs involving the relationship between temperature, pressure and volume for a fixed mass of an ideal gas.

• Solution of problems relating to the ideal gas equation.

• Explanation of the deviation of real gases from ideal behaviour at low temperature and high pressure.

• Obtaining and using experimental values to calculate the molar mass of a gas from the ideal gas equation.

• Solution of problems involving molar concentration, amount of solute and volume of solution.

• Use of the experimental method of titration to calculate the concentration of a solution by reference to a standard solution.

• The value of the Avogadro’s constant (L or NA) is given in the data booklet in section 2 and will be given for paper 1 questions.

• The ideal gas equation, 𝑃V = 𝑛RT , and the value of the gas constant (R) are given in the data booklet in sections 1 and 2.

• Units of concentration to include: g dm-3, mol dm-3 and parts per million (ppm).

• The generally used unit of molar mass (g mol-1) is a derived SI unit.