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A-LevelChemistryReaction kineticsMay/June 2023Paper 3 Q117 Marks

The thiosulfate ion, S2O3²⁻, decomposes when an acid is added. S2O3²⁻(aq) + 2H⁺(aq) → S(s) + SO2(aq) + H2O(l) The rate of this reaction can be investigated by measuring how long it takes the solution to produce enough sulfur so that it cannot be seen through. You will investigate how the concentration of the thiosulfate ion affects the rate of the reaction. Note: A small amount of sulfur dioxide gas may be formed in the experiment. It is very important that you avoid inhaling any fumes. As soon as each experiment is complete, empty the reaction mixture into the quenching bath and rinse the beaker thoroughly. FA 1 is 0.100 moldm⁻³ sodium thiosulfate, Na2S2O3. FA 2 is 2.00 moldm⁻³ hydrochloric acid, HCl.

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About This A-Level Chemistry Question

This structured question appeared in the Cambridge A-Level Chemistry (9701) May/June 2023 examination, Paper 3 Variant 1. It tests the topic of Reaction kinetics and is worth 17 marks.

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