This problem-solving activity, from the Royal Society of Chemistry, asks students to estimate the percentage of ‘empty space’ in a sample of gaseous argon. The key question which underpins this problem is ‘What is meant by the volume of a gas?’ and it can be approached in two ways: By calculating the space between the atoms or by calculating the space within the atoms and between the atoms. The methods for both approaches are provided and extension work is suggested.

Students need to work as a group to discuss the problem and decide how they are going to carry out the investigation. After the investigation, students prepare a presentation to give to their peers. Some prior knowledge of Avogadro’s number, the characteristics of solids, liquids and gases and the concept of atomic size is needed, though not in depth as students are encouraged to consult textbooks and data books during the exercise.

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This resource is part of Royal Society of Chemistry