Step 1: Calculate the moles of sucrose. PROBLEM: You dissolve 15.0 g of sucrose, C12H22O11, in a cup of water (225 g). What is the freezing point of the solution? NOTE: Kfp (H2O) = –1.86 ºC/m Step 1: Calculate the moles of sucrose. 15.0 g C12H22O11 x 1 mol C12H22O11/ 342.3 g = 0.0438 mol C12H22O11 Step 2: Calculate the molality of C12H22O11 0.0438 mol C12H22O11 / 0.225 kg H2O = 0.195 m Step 3: Calculate DTfp DTfp = kf • m • i – – > i = 1 since sucrose is molecular solid = –1.86 ºC/m • 0.195 m = –0.362 °C Tfp = –0.362 °C