# 4.3.5

4.3.5 Use of amount of substance in relation to volumes of gases (chemistry only) (HT only)

## Content

• Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure.

The volume of one mole of any gas at room temperature and pressure (20oC and 1 atmosphere pressure) is 24 dm3.

The volumes of gaseous reactants and products can be calculated from the balanced equation for the reaction.

Students should be able to:

• calculate the volume of a gas at room temperature and pressure from its mass and relative formula mass
• calculate volumes of gaseous reactants and products from a balanced equation and a given volume of a gaseous reactant or product
• change the subject of a mathematical equation.

WS 1.2Use a variety of models such as representational, spatial, descriptive, computational and mathematical to solve problems, make predictions and to develop scientific explanations and understanding of familiar and unfamiliar facts.

WS 4.1 Use scientific vocabulary, terminology and definitions.

WS 4.2 Recognise the importance of scientific quantities and understand how they are determined.

WS 4.3Use SI units (eg kg, g, mg; km, m, mm; kJ, J) and IUPAC chemical nomenclature unless inappropriate.

WS 4.6 Use an appropriate number of significant figures in calculation.

MS 1a - Recognise and use expressions in decimal form

MS 1c Use ratios, fractions and percentages

MS 3b Change the subject of an equation

MS 3c Substitute numerical values into algebraic equations using appropriate units for physical quantities