Question

Camphor melts at 179.8C and has a Kf = 40.0 C/m. When 0.186 g of an unknown nonvolatile nonelectrolyte is dissolved in 22.01 g of liquid camphor, the freezing point is found to be 176.7C. What is the molar mass of this solute?

Answer 1

179.8 − 176.7 = 3.1 °C
Δt = i Kf m

3.1 °C = (1) (40.0 °C kg mol¯1) (x / 0.02201 kg)

3.1 °C = (1) (1817.356 °C mol¯1) (x)

x = 0.001705775 mol

0.186 g / 0.001705775 mol = 109 g/mol