Question

Milk of magnesia, an over-the-counter antacid liquid, is a suspension of magnesium hydroxide in water. It neutralizes the hydrochloric acid in the stomach to alleviate some stomach symptoms associated with excess acid. In a laboratory, 1.12 g Mg(OH)2 is added to 235.9 mL of 0.1701 M HCl in water. They react according to the following equation. Mg(OH)2 + 2 HCl → MgCl2 + 2 H2O

(a) What is the limiting reagent in this reaction?

(b) How much magnesium chloride is produced?

Answer 1

a) Mg (OH)2

b) 1.12g (approximate)

Step-by-step explanation:

(a) To determine the limiting reagent, we need to compare the moles of Mg(OH)2 and HCl. First calculate the molar mass of Mg(OH)2:

Mg(OH)2 molar mass = mass / molar mass

Mg(OH)2 molar mass = 24.31 g/mol + 2 * (1.01 g/ mol + 16.00) ) g / mol) = 58.32 g / mol

Mg (OH) 2 mol = 1.12 g / 58.32 g / mol ≈ 0.0192 mol

Now, calculate the moles of HCl:

HCl mol = volume * HCl2 mol = 40 L concentration 444

1701 mol/L = 0.0401 mol

When we compare the moles, we see that Mg (OH) 2 is the limiting reagent as it has fewer moles (0.0192 mol) compared to HCl (0.0401 mol).

(b) The balanced equation shows that 1 mole of Mg(OH)2 produces 1 mole of MgCl2.

Thus, the amount of magnesium chloride produced will be equal to the Mg(OH)2 used. Thus, approximately 1.12 g of magnesium chloride is produced.