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3. (a) Answer ALL parts. The pressure-temperature phase diagram for carbon dioxide (CO2) is shown below. 10000 1000 CO solid 100 CO liquid A 10 Pressure (atm) B T 0.14 c CO, gas 0.01 - 0.0011 -140 120 100 80 60 40 -20 0 Temperature (0) 20 40 60 80 100 Using this phase diagram, answer the following questions: (i) Identify and discuss the significance of points A and B.
(ii) Using the phase rule, determine the number of phases (P), components (C) and the variance of the system (F) at points B, C and D. (b) [16 marks) Many important zeolite structures are based on the sodalite unit. Discuss using suitable diagrams, the composition and structure of the sodalite unit in terms of its: (1) Primary building units. (ii) Exchangeable cations and Si/Al ratio. (iii) Role in the formation of larger structures. [18 marks) Using a suitable diagram, write a note on the rate of diffusion as related to solid state reactions. [6 marks) (c)