Following are some standard Gibbs energies of formation, G 0f, per mole of metal

Question

Following are some standard Gibbs energies of formation, G0f, per mole of metal oxide at 1000 K: NiO,-115 kJ; MnO, -280 kJ;TiO2 -630 kJ. The standard Gibbs energy of formation of CO at 1000 K is -250 kJ per molCO.

Part A

Use the method of coupled reactions (page 851 in the textbook) to determine which of these metal oxides
can be reduced to the metal by a spontaneous reaction with carbon at 1000 K and with all reactants and products in their standard states.

The NiO can be reduced to the metal by

Part B

The MnO can be reduced to the metal by

Part C

The TiO2 can be reduced to the metal by

Explanation / Answer

a)

NiO(s) + C = Ni(s) + CO(g)

G = 0 - (-115 +-250) = 365 kJ

G > 0, cant be spontanoues

b)

MnO(s) + C = Ni(s) + CO(g)

G = 0 - (-280+-250) = 530kJ

G > 0, cant be spontanoues

c)

TiO2(s) + C = Ni(s) + CO(g)

G = 0 - (-630+-250) = 880 kJ

G > 0, cant be spontanoues

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