Earlier civilizations smelted iron from ore by heating it with charcoal from a wood fire: 

2Fe2O3(s) + 3C(s) —> 4F(s) + 3CO2(g) 

a) Write an expression for ΔG° as a function of temperature. Prepare a table of Delta ΔG° values at 100K intervals between 100K and 500K. 

b) Calculate the lowest temperature at which the smelting could be carried out.