Answer:
1. [OH⁻] = 2.4 x 10⁻¹⁴ M.
2. [H₃O⁺] = 4.167 x 10⁻¹ M.
Explanation:
Firstly, we need to calculate the molarity of Mg(OH)₂:
- Molarity (M) is the no. of moles of solute that dissolved in 1.0 L of the solution.
M = (no. of moles of solute)/(V of the solution (L).
∴ M of MgCl₂ = (no. of moles of solute)/(V of the solution (L) = (1.2 x 10⁻¹⁴ mol)/(1.0 L) = 1.2 x 10⁻¹⁴ M.
<u><em>1. [OH⁻]:</em></u>
- Mg(OH)₂ is dissociated in the solution according to the equation:
<em>Mg(OH)₂ → Mg²⁺ + 2OH⁻.</em>
<em></em>
- It is clear that every 1.0 mol of Mg(OH)₂ produces 2.0 moles of (OH⁻).
∴ [OH⁻] = 2(1.2 x 10⁻¹⁴) = 2.4 x 10⁻¹⁴ M.
<u><em>2. [H₃O⁺]:</em></u>
<u><em></em></u>
<em>∵ [H₃O⁺][OH⁻] = 10⁻¹⁴.</em>
∴ [H₃O⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(2.4 x 10⁻¹⁴ M) = 4.167 x 10⁻¹ M.