One molal solution of benzoic acid in benzene boils at . The normal boiling point of benzene is . As — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Elevation in boiling point $\Delta T_b = 81.53 - 80.10 = 1.43^\circ\text{C}$. For dimerization, $i = 1 - \alpha/2$. Given $\alpha = 0.90$, $i = 1 - 0.45 = 0.55$. Using $\Delta T_b = i \times K_b \times m$, we have $1.43 = 0.55 \times K_b \times 1 \Rightarrow K_b = 1.43 / 0.55 = 2.6 \text{ deg/molal}$. Therefore, correct answer is C.