Transcript PC

Experiment 3. Bomb Calorimetry
The picture here shows the Parr
bomb calorimeter that is illustrated
schematically on p. 153 of the lab
text. The bomb is illustrated in more
detail on the next page. After it is
prepared, it is inserted into the pail,
along with 2.00 L of water. Then the
lid is installed. It contains the stirring
assembly and a hole for inserting the
thermometer or (in our case)
thermistor. The adiabatic jacket
reduces but does not completely
eliminate heat flow between the
contents and the environment, which
is why we must use extrapolation
procedures.
2
The bomb is illustrated schematically
on p. 154 of the lab text. The instructor
will take you through the preparation of
the bomb for your first run. It is
important for both success and safety that
this be done correctly.
Perhaps the biggest source of failure
in this experiment is improper connection
of the fuse wire to the electrodes, or poor
contact between the wire and the pellet, so
take special care here.
We have never had an actual
explosion of a “bomb.” Please don’t
become our first!
3
One of our biggest sources
of frustration in connection with
this experiment is students
leaving chemical “crumbs” in
the work area near the balances.
Your pellets will mostly already
be of a size suitable for use in
the experiment, but if you do
need to reduce their size,
remember to clean up and
properly dispose of any
shavings.
As always, be considerate of your fellow scholars!