I'm sorry, but the given chemical equation does not balance correctly. Here is the balanced equation for the reaction of hydrogen gas (H2) with copper(II) oxide (CuO) to form water (H2O), hydrogen gas (H2), hydrogen chloride gas (HCl), and magnesium chloride (MgCl2):

2H2 + 2CuO → 2H2O + 2Cu + H2 + 2Cl2 + MgCl2

It is important to note that the formation of magnesium chloride (MgCl2) was not part of the original equation provided. Please let me know if you have any further questions.