Question

22. 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: Ni(s) + 4CO(g) = Ni(CO)4(g) For Ni(CO) (g) the AH° = 607 kJ/mol and Sº - 417 J/K mol J/ Kmol, for CO(g) the AH = -110.5 kJ/mol and Sº = 198 J/K mol, and for Ni(s) the Sº = 30.0 J/K.mol at 298 K. The first step of the Mond process involves equilibrating impure nickel with and at about 50°C. 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°C.

Answer 1

Ans. The given reaction is Nils) + 4.00 (g) 3 Nilco.lu .cg) buiven enthalpy of formation of .. each compound is .. _AHO [ Nils)] = 0 • As enthalpy of formation for an element in its standard state is zero Hence Hornils) = 0 (suiven, OHO [ colg)] = -110.5 kJ/mol T AHO [Ni(0)4] = -607 kJ/mol We can calculate enthalpy of reaction from enthalpy of formation using the formula.

OH reaction = AHO [ Products ] - Atol Reactant for the given Reaction Nils) + 4 colo) z Ni Clony Lg) o Hireaction = A HOI Ní Ccody 9)] – AHO [wils)]- 4.0 Hºſ Colg)] =-607 - 0 - (-110.5) x4 -_-_-607 + 4 X 110.5 → AH reaction = -165 kJ Hence enthalpy of reaction is - 165 kJ The entropy of the compound is so (Nics)] = 30 J/mol-K: So I CO (9] = 198.Jl melk Sº [ Nilw0Oylgi] = 417 J/mol k

We can calculate entropy of reaction using formula As reaction = so [ Products) - 50 [ Reactant] - So [NiCCM)4 4)] - So[ Nils] :- 450 [co la = 417 - 30 - 4x198 As reaction = -405 JK Entropy of Reaction is -405 J/K ol A5º = -405 X10-3 kJ/ K Now , we can calculate bubb's free energy for the reaction (Alerxn) using formula Alge - AH'- JASO T = Temperature = 298 K. 8x h. _

. Alyon = A.Hoxn - JASON Aliran = -165 - 298% (-405X10-31 ___-165 +298 x 405 X 10-3 E-165 + 120.69 Doxn = - 44.31 kJ Equilibrium constant (K) can be calculated from Aloron using the q formula AG0 = - RT Im k AG0 - 20303 RT loquiok Here R = Gras Constant = 8.314 of mol K T = 298.K Tren

- Alyson = -44.81 KJ = -44-31 x 103 J Thus Ayº = - 20303 X.RT logio Kog g -44.31.x. 103 = -2.303 x 8.314 X - 2988 logo keg g loa Keg = 44.31 x 103 20303 x 3.314 x 298 & logio keq = 7.766 Taking Antilog Reg = Antilog 17.766) Keq = 5084 X107. Thus, the equilibrium constant for the given Reaction is 5084X107

Equilibrium constant , K = 5.84 ×107