Question

A chemist reacts 30.0 mL of 5.6 M HCl with an excess of Mg(OH)2 How many grams of magnesium will be produced

Answer 1

2.042 g

Step-by-step explanation:

The reaction that takes place is:

• 2HCl + Mg(OH)₂ → Mg²⁺ + 2Cl⁻ + 2H₂O

First we calculate how many HCl moles were added, using the given volume and concentration:

• 30 mL ⇒ 30 / 1000 = 0.030 L

• 5.6 M * 0.030 L = 0.168 mol HCl

Then we convert HCl moles into Mg²⁺ moles, using the stoichiometric coefficients:

• 0.168 mol HCl *
  `(1molMg^(+2))/(2molHCl)`= 0.084 mol Mg⁺²

Finally we convert Mg moles into grams, using its molar mass:

• 0.084 mol Mg⁺² * 24.305 g/mol = 2.042 g