Calculate the mass of magnesium chloride, which is obtained by the interaction of 64 g of magnesium with hydrochloric acid.

We compose the equation of the proceeding reaction:
2HCl + Mg = MgCl2 + H2.
1) According to the periodic table, the molar mass of magnesium is 24.
2) Find the amount of magnesium substance. For this, the mass of magnesium is divided by its molar mass: 64/24 = 2.7 mol.
3) According to the reaction equation, one mole of magnesium accounts for one mole of magnesium chloride. This means that the amount of magnesium chloride substance is 2.7 mol.
4) Molar mass of magnesium chloride: 24 + 35.5 * 2 = 95.
5) Mass of magnesium chloride: 95 * 2.7 = 256.5 g – the answer.