There is more redox chemistry in the workup. Excess iodine reacts with thiosulfate to form iodide and dithionate: I2 (aq) + 2 S2O3 2– (aq) → 2 I– (aq) + S4O6 2– (aq) What is the practical advantage of reducing excess iodine to iodide (i. e. how does this make it easier to collect pure product)?

One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(ii) carbonate, in concentrated sulfuric acid. the sulfuric acid reacts with the copper(ii) carbonate to produce a blue solution of copper(ii) sulfate. scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: (s) (aq) (s) (aq) suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. he adds powdered iron to a copper(ii) sulfate sample from the plant until no more copper will precipitate. he then washes, dries, and weighs the precipitate, and finds that it has a mass of .