A 50.6 grams sample of magnesium hydroxide (Mg(OH)2) is reacted with 45.0 grams of hydrochloric acid (HCl). What is the theoretical yield of magnesium chloride (MgCl2) Mg(OH)2 plus 2 HCl MgCl2 plus 2?

Answer 1

To determine the theoretical yield of magnesium chloride (MgCl₂) from the reaction of magnesium hydroxide (Mg(OH)₂) with hydrochloric acid (HCl), we first identify the balanced chemical equation: Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O. The molar mass of Mg(OH)₂ is approximately 58.3197 g/mol, and that of MgCl₂ is about 95.211 g/mol.

Calculating the moles of Mg(OH)₂ in 50.6 g gives about 0.868 moles, while 45.0 g of HCl corresponds to about 1.23 moles. Since the reaction requires 2 moles of HCl for every mole of Mg(OH)₂, HCl is in excess. The limiting reagent is Mg(OH)₂, producing 0.868 moles of MgCl₂. Therefore, the theoretical yield of MgCl₂ is approximately 82.7 grams (0.868 moles × 95.211 g/mol).