A-LevelChemistryAnalytical techniquesMay/June 2024Paper 3 Q215 Marks
2 Iodate ions contain iodine and oxygen. They have the formula IOx⁻ where x is an integer. In this experiment you will determine the value of x in an iodate. You will first react IOx⁻ with an excess of iodide ions, I⁻, to form iodine, I2. The amount of iodine produced is then determined by titration with thiosulfate ions, S2O3²⁻. I2(aq) + 2S2O3²⁻(aq) → 2I⁻(aq) + S4O6²⁻(aq) FB 2 is 0.100 mol dm⁻³ sodium thiosulfate, Na2S2O3. FB 3 is a solution containing 0.0140 mol dm⁻³ IOx⁻ ions. FB 4 is dilute sulfuric acid, H2SO4. FB 5 is 0.500 mol dm⁻³ potassium iodide, KI. FB 6 is starch indicator.
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