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DTf = -kfmA
Example. What
is the freezing point of ocean water containing approximately
one NaCl per 100 water molecules, or one mole of NaCl
per 100 moles of H2O as described previously
in this chapter?
Solution
Colligative properties were the basis for one of the
original proofs that salts really did dissociate, and
for determining how many ions were produced. For example,
one could imagine that the compound potassium ferricyanide,
K3Fe(CN)6 dissociates in solution
as follows:
Is this true? A freezing-point experiment can settle
the matter.
Example. When
300 mg of potassium ferricyanide are dissolved in 10
ml of water, the freezing point falls to -0.68°
C. How many ions are produced by one K3Fe(CN)6
formula unit?
Solution
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