Law of conservation of mass (Edexcel GCSE Chemistry & Combined Science)

This lesson explains the law of conservation of mass and applies this law to a closed system and a non-enclosed system. The PowerPoint and accompanying resources have been designed to cover point 1.48 of the Edexcel GCSE Chemistry specification and also covers that point in the Chemistry section of the Combined Science course.

The lesson begins by introducing the law of the conservation of mass. Students will learn that they can expect questions which challenge them to prove that mass is conserved through the use of the relative formula mass. Therefore, the next section of the lesson focuses on the skills associated with this calculation and looks at more different formulae such as those with brackets. Students are given an opportunity to check their skills before trying to prove mass is conserved in three chemical reactions. All questions have displayed mark schemes so that students can assess their understanding. The rest of the lesson looks at instances of when the mass of the reactants does not equal the mass of the products. A practical method for the decomposition of copper carbonate is provided if the teacher wants to use it, so that students can collect results which show this difference in mass. Discussions are encouraged in order to get students to offer explanations as to why the mass of the products is lower. Once the gas has been identified, students are further challenged to consider apparatus that could be used to collect and record the results to again prove conservation