1. 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/ g = mol C12H22O11
Step 2: Calculate the molality of C12H22O11
mol C12H22O11 / kg H2O = m
Step 3: Calculate DTfp
DTfp = kf • m • i – – > i = 1 since sucrose is molecular solid
= –1.86 ºC/m • m = –0.362 °C
Tfp = –0.362 °C