Mining companies extract iron from iron ore according to the following balanced equation:

Fe2O3(s)+3CO(g)2Fe(s)+3CO2(g)Fe2O3(s)+3CO(g)2Fe(s)+3CO2(g)

In a reaction mixture containing 167 gg Fe2O3Fe2O3 and 85.8 gg COCO, COCO is the limiting reactant.

Calculate the mass of the reactant in excess (which is Fe2O3 ) that remains after the reaction has gone to completion. Express the mass with the appropriate units.