8 (A410U10-1) Examiner only 10. Industrial processes are designed to give the maximum yield of the pure product in the shortest time at the lowest possible cost. The choice of temperature, pressure and catalyst are all key factors of designing an industrial process. (a) (i) The Wacker process is used to produce ethanal from ethene. It is a reaction catalysed by a mixed catalyst containing chlorides of copper and palladium. The reaction may be carried out in the gas phase according to the equation below. C2H4(g) + 1 2 O2(g) [ CH3CHO(g) ΔHθ = –218 kJ mol−1 Outline the factors that would need to be considered when selecting conditions for this process, applying these to suggest appropriate conditions. You should include a full explanation of why catalysts are very important for exothermic equilibria such as this. [6 QER] © WJEC CBAC Ltd. (A410U10-1) Turn over. A 410 U101 0 9 9 Examiner only (ii) This industrial process has a yield of 95.0 %. Calculate the mass of ethanal, in kg, that would be produced from 2.00 tonnes of ethene. [3] Mass of ethanal = ........................................................ kg (b) This process uses a catalyst mixture that contains CuCl2. When copper(II) compounds are dissolved in water they appear pale blue, whilst copper(I) compounds are not coloured. (i) Give the formula of the complex ion present in dilute aqueous solutions of copper(II) compounds. [1] (ii) Explain why copper(I) compounds are not coloured. [2] (iii) State the colour change that occurs when concentrated ammonia solution is added to copper(II) compounds in aqueous solution, drawing the structure of the copper- containing ion present. Explain why the addition of ammonia solution causes the colour to change. [4] © WJEC CBAC Ltd. 16