The chemical equation below shows the burning of magnesium (mg) with oxygen (o2) to form magnesium oxide (mgo). 2mg + o2 mc019-1.jpg 2mgo niven wants to calculate the mass of mgo that is produced by the burning of 28.0 g of mg. what is the first step in niven’s calculation? balance the chemical equation. convert grams of mg to moles. determine whether heat is given off by this reaction. find the number of mg atoms in the sample. the answer is b. convert grams of mg to moles.