Question

Chloroform, CHCl₃, boils at 61.7°C. If Kb for chloroform is 3.63°C/molal, what is the boiling point of a solution of 15.0 g of CHCl₃ and 0.616 kg of acenaphthalene (C₁₂H₁₀)?

• A. \(61.9^\circ\text{C}\)
• B. \(62.0^\circ\text{C}\)
• C. \(52.2^\circ\text{C}\)
• D. 62.67°C

Hint:

Boiling point elevation depends only on number of solute particles.

Answer 1

The Correct Option is D

Step 1: Moles of solute: \( n = \frac{15}{154} \approx 0.0974 \) 

Step 2: Molality: \( m = \frac{0.0974}{0.616} \approx 0.158 \) 

Step 3: Elevation in boiling point: \( \Delta T_b = K_b \cdot m = 3.63 \times 0.158 \approx 0.57 \) 

Step 4: Boiling point: \( T_b = 61.7 + 0.57 \approx 62.27^\circ\text{C} \)