Hydrogen chloride gas is made in the laboratory by adding concentrated sulfuric acid to potassium chloride.

1. (a)Hydrogen chloride gas is made in the laboratory by adding concentrated sulfuric acid to potassium chloride.
2. (a)(i)Construct an equation for this reaction.[1]
3. (a)(ii)Explain why hydrogen iodide is not prepared by adding concentrated sulfuric acid to sodium iodide.[2]
4. (b)A sample of HI(g) is added to a 2.00dm³ sealed vessel at 764K and allowed to reach equilibrium. reaction 1 2HI(g) ⇌ H2(g) + I2(g) Kc = 0.0217 at 764 K At equilibrium the mixture contains 1.70 mol of HI(g).
5. (b)(i)State one difference in the appearance of the initial reaction mixture compared to the mixture at equilibrium.[1]
6. (b)(ii)Deduce the expression for equilibrium constant Kc for reaction 1. Kc =[1]
7. (b)(iii)Calculate the concentration of I2 present in the reaction mixture at equilibrium. Show your working. concentration of I2 = ...................................... mol dm⁻³[3]
8. (c)The experiment is repeated at 500K. The value of Kc under these conditions is 0.00625.
9. (c)(i)Describe the difference in the composition of the equilibrium mixture at 500K compared to 764 K.[1]
10. (c)(ii)Use Le Chatelier's principle to deduce whether the decomposition of HI(g) is endothermic or exothermic. Explain your answer.[1]