Transcript Mac

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 equilibrium, and if the thermistor probe is not centered,
it can be hit by the stirring loop, with disastrous
consequences.
!
Quic kTime™ and a
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are needed to see this pic ture.