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Determining Ea for a reaction

This Higher Level practical builds on one of the classic experiments normally used at a pre-IB Diploma level (e.g. GCSE) to show the factors affecting the rate of a chemical reaction. This experiment is variously known as ‘the cross on a tile’ or the disappearing cross’ reaction and involves the reaction between sodium thiosulfate and hydrochloric acid.S2O32– (aq) + 2H+(aq) → SO2(g) + S(s) + H2O (l)

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