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**dTf = (Kf)(m)**

dTb = (Kb)(m)

dTb = (Kb)(m)

*d*= change of

*Tf*= freezing point depression

*Tb*= boiling point elevation

*K*= constant

*m*= molality (mol/kg)

However, in my chemistry textbook, the same formulas are described as:

**dTf = (Kf)(m) x i**

dTb = (Kb)(m) x i

dTb = (Kb)(m) x i

*i*= van't hoff factor?

Are they the same formulas? Why do you think Kaplan choose to neglect the

*i*?

--- --- ---

I solved the following problem using Kaplan's method, which doesn't utilize the i:

Question:

**A solution contains 10 g of CH4N2O dissolved in 150 g of water. If the molal freezing-point-depression constant for water is 1.86 (C x kg) / mol, what is the solution's freezing point?**

Answer:

dTf = Kf x m

dTf = [1.86 (C x kg) / mol)](1.11 mol/kg)

dTf = 2.07 C

freezing point = 0 C - freezing point depression (dTf)

freezing point = 0 C - 2.07 C =

**-2.07 C**

Are there questions out there that require you to use the

*i*? If so, point me in that direction please.