Chlorate(I) ions undergo the following reaction under aqueous conditions. 2NH3 + ClO⁻ → N₂H₄ + Cl⁻ + H₂O A series of experiments was carried out at different concentrations of ClO⁻ and NH3. The table shows the results obtained. [Table 5.a: experiment | [ClO⁻] /mol dm⁻³ | [NH3] /mol dm⁻³ | initial rate /mol dm⁻³s⁻¹ 1 | 0.200 | 0.100 | 0.256 2 | 0.400 | 0.200 | 2.05 3 | 0.400 | 0.400 | 8.20]

1. (a)(i)Use the data in the table to determine the order with respect to each reactant, ClO⁻ and NH3. Show your reasoning.[2]
2. (a)(ii)Write the rate equation for this reaction. rate =[1]
3. (a)(iii)Use the results of experiment 1 to calculate the rate constant, k, for this reaction. Include the units of k. k = units =[2]
4. (a)(iv)On the axes sketch a graph to show how the value of k changes as temperature is increased. [Figure 5.a.iv][1]
5. (b)(i)In another experiment, the reaction between chlorate(I) ions and iodide ions in aqueous alkali was investigated. A solution of iodide ions in aqueous alkali was added to a large excess of chlorate(I) ions and [I⁻] was measured at regular intervals. Describe how the results of this experiment can be used to confirm that the reaction is first-order with respect to [I⁻].[2]
6. (b)(ii)A three-step mechanism for this reaction is shown. step 1 ClO⁻ + H₂O → HClO + OH⁻ step 2 I⁻ + HClO → HIO + Cl⁻ step 3 HIO + OH⁻ → H₂O + IO⁻ Use this mechanism to deduce the overall equation for this reaction.[1]
7. (b)(iii)Identify a step that involves a redox reaction. Explain your answer.[1]

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