DETERMINATION OF THE RESONANCE ENERGY OF BENZENE
Reading Assignment:
- We are
doing Experiment 6 from Halpern, involving
determining the heat of combustion of the compound 1,5,9-trans,
trans, cis-cyclododecatriene (CDDT). But, the procedure is discussed in Expt. 5 of Halpern, so you
need to read that also. Start
reading on page 125, The Calorimeter and go to p. 131 bottom. We will calibrate the apparatus using
benzoic acid, but instead of naphthalene, you will use liquid cyclododecatriene (CDDT).
- The
instructor will show the instrument specialists how to use the bomb
calorimeter, who in turn will explain it to the other member of the group.
- First
week you will calibrate the calorimeter using benzoic acid pellets,
that is determining its calorimetry constant C,
which is different for each apparatus.
The value should be somewhere in the range of 10 kJ/°C. You will need to correct for the
ignition wire burned, but not for the formation of nitric acid from
nitrogen gas in the bomb. Do two
runs with benzoic acid and take the average value of C as the calorimeter
heat capacity.
- The second
week you will do the CDDT combustion (twice). Also do the resonance energy of benzene calculation
on CAChe.
- During
your spare time in the first week, probably after completing the two runs
with benzoic acid, lets try to run through the
tutorial for CAChe. It is loaded on the computers in 102C.
- Include
in your report the Supplemental Activity: Computational Determination of
the Resonance Energy of Benzene. See directions on page 142, Halpern.
- It
would be a good idea to construct and save on your disk the structures of
benzene, chair cyclohexane and CDDT (correct
isomer!).
- Literature
sources for DHcomb°
and DHf°
can be found in the Handbook of Chemistry and Physics or on-line: http://webbook.nist.gov/