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In the Kaplan blue book, the formulas for freezing point depression and boiling point elevation (pg. 274) are described as:
dTf = (Kf)(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
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.
dTf = (Kf)(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
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.