Experiment 6. Freezing Point Depression

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Experiment 6. Freezing Point Depression
In this experiment, acid solutions are mixed
with ice in an insulated flask and are stirred
until the system achieves equilibrium. This is
indicated by no further change in the
temperature, which is sensed by a thermistor
probe and displayed on the computer monitor. A
sample of the acid solution is then extracted and
titrated to determine its acid content. The
procedure is repeated for a range of acid
concentrations. It is wise for the partners to
share responsibilities in such a way that one
manages the stirring and sampling, while the
others handle solution preparation and titration.
In this way the data are easily collected in the
allotted time.
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It is important that the thermistor probe be
installed as close to vertical as possible, so
that it is centered in the stirring loop. It is
necessary to stir the mixture vigorously to
achieve equilib-rium, and if the thermistor probe
is not centered, it can be hit by the stirring
loop, with disastrous consequences.
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