13618.06R 12 Concentrated sulfuric acid reacts with the solids, sodium chloride, sodium bromide and sodium iodide. Concentrated sulfuric acid is a source of sulfate ions. (a) Give the systematic name of the sulfate ion. [1] (b) The reaction between concentrated sulfuric acid and solid sodium chloride is not a redox reaction. One of the products is hydrogen chloride. (i) Write an equation for this reaction. [1] (ii) Describe a test which would indicate the presence of hydrogen chloride. [2] (c) During the reaction between concentrated sulfuric acid and solid sodium bromide, hydrogen bromide is formed and oxidised by the acid. Write an equation for oxidation of hydrogen bromide by concentrated sulfuric acid. [2] (d) Iodide ions are stronger reducing agents than bromide ions. (i) Define reducing agent. [1] (ii) Suggest why iodide ions are stronger reducing agents than bromide ions. [1] 13618.06R [Turn over (e) When concentrated sulfuric acid is added to solid sodium iodide, iodine and three sulfur containing products are formed. (i) Determine the oxidation state of sulfur in each of the following sulfur containing products. SO2 S H2S [2] (ii) What observation would suggest the formation of H2S in this reaction? [1] (iii) What observation would suggest the formation of sulfur in this reaction? [1] (iv) Complete the half-equation for the formation of H2S. SO2 4 -      +      H+      +        →    H2S      +      H2O [2] (v) Write a half-equation for the formation of iodine. [1] (vi) Combine the half-equations in (e)(iv) and (e)(v) to give a balanced redox equation. [1]