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2. (a) Answer ALL parts. Antimony-bismuth is an alloy which finds applications in semiconductor and thermoelectric devices. The phase diagram for the antimony-bismuth system is shown below. A sample of composition 60 wt% Sb is made up at held at 400 °C. Based on this information and the phase diagram below, answer the following questions: (i) What is the melting point of pure bismuth (Bi) and antimony (Sb)? (i) What is the composition of any solid phase present? (ii) What is the composition of any liquid phase present? (iii) How much of each phase is present?
650- 600 550 Liquid (L) 500) 450 Temperature (°C) Q+L 400 350) 300 Solid (a) 250 2001 0 Bi 10 60 90 20 30 40 50 70 80 Composition (wt% Sb) 100 Sb [17 marks] (b) Zeolite materials have found applications as shape selective catalysts due to the widely available variety of zeolites with differing pore and channel sizes. Describe three types of shape selective catalysis. Use suitable diagrams and examples to illustrate your answer. [15 marks) (c) Using suitable diagrams, describe why the rate of solid state reactions slows as the reaction proceeds. [8 marks)