Cement production accounts for 1% of anthropogenic emission of carbon dioxide. During a pyrolysis reaction, calcium carbonate ( CaCO3) is heated to temperatures greater than 500c to produce calcium oxide (CaO) and carbon dioxide. CaO makes up approximately 65% of commercial cement. The other ingredients include silicon dioxide (SiO2, 25%) aluminum (III) oxide (Al2O3, 4%) , ferrous (III) oxide (Fe2O3, 3%) and magnesium oxide (MgO, 3%) write a balanced equation?