Moles and the Mole Concept
Students need to be able to inter convert comfortably between moles and masses at this stage and understand how to use the data in the periodic table to work out how much one mole of a substance is, whether an element or a compound.
Students often have misconceptions regarding balanced chemical equations, and in particular will often still not be clear about the different numbers used in formulae and equations. For example if 2 Mg(NO3)2 appears in an equation students are often still unclear at this stage about the meaning of the stoichiometry number and the use of the subscript in NO3 and the importance of the subscript outside the brackets. It is absolutely essential that any issues of this kind are addressed before moving on to any sort of calculations involving balanced chemical equations.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance
Links and Resources
Although this book is somewhat dated in years ideas about the mole have not changed since it was printed. It contains many example calculations that can be used to give students practice in converting moles to masses and vica versa. It also contains, in the first section, a number of very useful and tactile activities that students can carry out in order to understand the concept of relative atomic mass, an otherwise relatively abstract idea that students will often struggle with. This is a book rich in ideas to help students understand the mole concept and become proficient in its application. Perhaps the only negative is that solutions to the problems are not included.
This short video sequence shows a group of younger students exploring the idea of conservation of mass with their teacher. Three "reactions" are considered and used as a focus to stimulate discussion of what had happened and how the observations support the Law of Conservation of Mass. At this level the discussion was kept simple but could easily be extended to include more sophisticated ideas suitable for an older age group.
In this simple micro scale experiment from the RSC students carry out two chemical reactions weighing the equipment before and after the reaction. The results lead to a discussion of the Law of Conservation of Mass. Brief notes and a student worksheet are included.
The first worksheet in this collection (section 1.1.1) covers simple calculations involving mass and moles. The resource itself is a collection of worksheets on all areas of chemical calculations. Answer to the problems are included.
This ICT based activity challenges students to think about combining quantities in chemical reactions and is a nice lead in fro the mole concept to starting to apply the concept to reacting mass calculations. Specifically it addresses the idea of limiting reactants when there is more of one reactant than the other in terms of the molar ratios. It is a useful activity to get students thinking about stoichiometry and its importance in chemistry. This lead to an understanding of why chemists need to calculate required quantities of reactants before running a reaction and the purpose of reacting mass calculations. The animations start by using the analogy of making sandwiches before moving on to apply the same basic concepts to chemical reactions.