Answer to Question #302123 in General Chemistry for Hutchii

Question

The boiling point of chloroform increased by 3.68 degrees C when 0.167 g of an unknown sample was dissolved in 1.00 g of chloroform (Kb = 3.63 degrees C/m). Find the molar mass of the unknown compound.

Answer 1

∆T_b = 3.68 °C

K_b = 3.63 °C/m

∆T_b = K_b × m = K_b × n solute / m solvent(kg) = K_b x m solute / (Mr solute x m solvent(kg))

3.68 °C = 3.63 °C kg/mol × 0.167 g × 1000 / (Mr × 1.00 g)

Mr = 164.73 g/mol