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Conservation of Mass



Three lesson planning ideas for short, snappy chemistry experiments for Key Stage 3 lessons, designed to help pupils explore the principle of conservation of mass.

Chemistry teacher Jack Forrest carries out a number of quick and simple experiments with his Year 7 class, to reinforce the idea that mass is always conserved. These experiments would also work well with lower age groups.

First, the students mix colourless solutions of potassium iodide and lead nitrate together, to form a bright yellow mixture, demonstrating that a chemical reaction has taken place. They weigh the solutions before and after mixing, noting that the mass remains the same.

Next, Jack demonstrates a classic Carbonate reaction, reacting marble chips and hydrochloric acid. The class discuss why the mass decreases in this reaction. Lastly, he cooks popcorn kernels which increase in volume when boiled, but the mass stays the same.

Published : Nov 2010

05 mins


Great Secondary Lesson Ideas


Secondary Teacher


Secondary Science



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