Colligative Constants Constants for freezingpoint depression

Colligative Constants Constants for freezing-point depression and boiling-point elevation calculations at 1 atm: Formula Kf value Normal freezing Kb value Normal boiling H20 1.860.00 C6H6 5.12 (OC/m) point (oc) c/m) point (c) 0.512 100.00 2.53 2.92 1.22 water 80.1 80.7 78.4 benzene 5.49 6.59 cyclohexane H12 20.8 ethanol carbon C2H60 1.99 CCl4 29.8 -22.9 5.03 76.8 tetrachloride camphor C10H160 37.8 176 \"When using positive Kf values, assume that is the absolute value of the change in temp temperature, then Tf will be negative and so you must use negative Kf values. Either way, t solvent. Comments

Solution

2.71 m K3PO4(aq).

molality of K3PO4 = 2.71 m

i = number of ions = 4

delta Tf = i x Kf x m

0.00 - Tf = 4 x 1.86 x 2.71

Tf = - 20.16 oC

freezing point = - 20.2 oC

delta Tb = i x Kb x m

Tb - 100 = 4 x 0.512 x 2.71

Tb = 105.55 oC

boiling point = 105.55 oC