Answer:
103.06°C.
Explanation:
- To solve this problem, we can use the relation:
<em>ΔTb = i.Kb.m,</em>
Where, i is the van 't Hoff factor.
Kb is the molal boiling point elevation constant of water (Kb = 0.51°C/m).
m is the molality of the solution (m = 2.0 m).
- We need to define and find the van 't Hoff factor (i):
<em>van 't Hoff factor</em> is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass.
- Mg(ClO₄)₂ is dissociated according to the equation:
<em>Mg(ClO₄)₂ → Mg²⁺ + 2ClO₄⁻,</em>
1 mol of Mg(ClO₄)₂ produces 3 mol of ions (1 mol Mg²⁺ and 2 mol ClO₄⁻).
∴ i = 3/1 = 3.
∴ ΔTb = i.Kb.m = (3)(0.51 °C/m)(2.0 m) = 3.06 °C.
∵ ΔTb = the boiling point in presence of solute (Mg(ClO₄)₂) - the boiling point of pure water.
The boiling point of pure water = 100.0°C.
<em>∴ The boiling point in presence of solute (Mg(ClO₄)₂) = ΔTb + the boiling point of pure water =</em> 3.06 °C + 100.0°C = <em>103.06°C.</em>
