Question

In the Mond process for the purification of nickel, carbon monoxide is reacted with heated nickel to produce Ni(CO)₄, which is a gas and can therefore be separated from solid impurities:

Ni(s) + 4CO(g) ⇌ Ni(CO)₄(g)

Given that the standard free energies of formation of CO(g) and Ni(CO)₄(g) are

−137.3 and −587.4 kJ/mol,

respectively, calculate the equilibrium constant of the reaction at

78.0

°

C.

Assume that

Δ

G

o

f

is temperature-independent.

Answer 1

we have:

Gof(Ni(s)) = 0.0 KJ/mol

Gof(CO(g)) = -137.3 KJ/mol

Gof(Ni(CO)4(g)) = -587.4 KJ/mol

we have the Balanced chemical equation as:

Ni(s) + 4 CO(g) ---> Ni(CO)4(g)

deltaGo rxn = 1*Gof(Ni(CO)4(g)) - 1*Gof( Ni(s)) - 4*Gof(CO(g))

deltaGo rxn = 1*(-587.4) - 1*(0.0) - 4*(-137.3)

deltaGo rxn = -38.2 KJ/mol

deltaGo rxn = -38200 J/mol

T= 78.0 oC

= (78.0+273) K

= 351 K

we have below equation to be used:

deltaG = -R*T*ln Kc

-38200 = - 8.314*351.0* ln(Kc)

ln Kc = 13.0902

Kc = 4.84*10^5

Answer: 4.84*10^5