The chemical equation below shows the burning of magnesium (mg) with oxygen (o2) to form magnesium oxide (mgo). 2mg o2 right arrow. 2mgo the molar mass of o2 is 32.0 g/mol. what mass, in grams, of o2 is required to react completely with 4.00 mol of mg? 2.00 grams 64.0 grams 128 grams 256 grams