Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted

Chapter 17, Problem 17.147

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Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted into metal from 99.90% to 99.99% purity by the Mond process. The primary reaction involved in the Mond process is Ni1s2 1 4CO1g2mNi1CO2 4 1g2 a. Without referring to Appendix 4, predict the sign of DS8 for the above reaction. Explain. b. The spontaneity of the above reaction is temperaturedependent. Predict the sign of DSsurr for this reaction. Explain. c. For Ni(CO)4(g), DH8f 5 2607 kJ/mol and S8 5 417 J/K mol at 298 K. Using these values and data in Appendix 4, calculate DH8 and DS8 for the above reaction. d. Calculate the temperature at which DG8 5 0 (K 5 1) for the above reaction, assuming that DH8 and DS8 do not depend on temperature.e. The first step of the Mond process involves equilibrating impure nickel with CO(g) and Ni(CO)4(g) at about 508C. The purpose of this step is to convert as much nickel as possible into the gas phase. Calculate the equilibrium constant for the above reaction at 50.8C. f. In the second step of the Mond process, the gaseous Ni(CO)4 is isolated and heated to 2278C. The purpose of this step is to deposit as much nickel as possible as pure solid (the reverse of the preceding reaction). Calculate the equilibrium constant for the preceding reaction at 2278C. g. Why is temperature increased for the second step of the Mond process?h. The Mond process relies on the volatility of Ni(CO)4 for its success. Only pressures and temperatures at which Ni(CO)4 is a gas are useful. A recently developed variation of the Mond process carries out the first step at higher pressures and a temperature of 1528C. Estimate the maximum pressure of Ni(CO)4(g) that can be attained before the gas will liquefy at 1528C. The boiling point for Ni(CO)4 is 428C and the enthalpy of vaporization is 29.0 kJ/mol. [Hint: The phase change reaction and the corresponding equilibrium expression are Ni1CO2 4 1l2mNi1CO2 4 1g2 K 5 PNi1CO2 4 Ni(CO)4(g) will liquefy when the pressure of Ni(CO)4 is greater than the K value.]