②3Fe2O3(s)+CO(g)═2Fe3O4(s)+CO2(g)△H2=﹣50.75kJ/mol
③Fe3O4(s)+CO(g)═3FeO(s)+CO2(g)△H3=﹣36.5kJ/mol
则反应:2FeO(s)+2CO(g)═2Fe(s)+2CO2(g)的△H=.