Question

For the equation:

MnO2 (s) + 2 CO (g) ? Mn (s) + 2 CO2 (g) what is the ?G

Answer 1

The given chemical reaction is

MnO2 (s) + 2 CO (g) -------------> Mn (s) + 2 CO2 (g)

Let us find delta H value from the Hf values given.

Delta H = [(Hf of Mn) + 2(Hf of CO2)] - [(Hf of MnO2) + 2(Hf of CO)]

Delta H = [(0) + 2(-393.51)] - [(-520.03) + 2(-110.54)]

Delta H = -45.91 kJ/mol

Let us find delta S value from the So values given.

Delta S = [(So of Mn) + 2(So of CO2)] - [(So of MnO2) + 2(So of CO)]

Delta S = [(32.01) + 2(213.68)] - [(53.05) + 2(197.90)]

Delta S = 10.52 J/mol K = 0.01052 kJ/mol K

Delta G = Delta H - T(Delta S)

T = 125 oC = 398 K

Delta G = -45.91 - (398)(0.01052)

Delta G = -45.91 - 4.187

Delta G = 50.1 kJ/mol