The balanced chemical equation for the synthesis reaction between magnesium and oxygen to form magnesium oxide is:2 Mg + O 2 MgOTo find the mass of magnesium oxide produced, we need to use stoichiometry. First, we need to find the molar mass of magnesium and magnesium oxide:Mg: 24.31 g/molMgO: 24.31 g/mol for Mg + 16.00 g/mol for O = 40.31 g/molNow, we can use the given mass of magnesium 5 grams to find the moles of magnesium:moles of Mg = 5 g / 24.31 g/mol = 0.2056 molAccording to the balanced equation, 2 moles of Mg produce 2 moles of MgO. Therefore, the moles of Mg and MgO are in a 1:1 ratio. So, we have 0.2056 moles of MgO produced.Finally, we can find the mass of magnesium oxide produced:mass of MgO = 0.2056 mol 40.31 g/mol = 8.29 gSo, 8.29 grams of magnesium oxide will be produced if 5 grams of magnesium reacts with excess oxygen.