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C-8
B.
Sugar (sucrose: C
12
H
22
O
11
)
Note that the formula for sucrose is not C
12
11 H2O, therefore, units of water molecules are not present in
sucrose.
1.
Only for this part of the experiment, obtain a disposable test tube from your laboratory instructor.
Put a few crystals of sugar into it. Heat the sugar following the procedure used in A.1 and A.2 of
Part II. There will be a smell of caramel (think of toasted marshmallows). Is there evidence that
water is present?
2.
Continue to heat until a brown/black solid residue is formed. Cool the test tube, then add a few
drops of water to the residue. Record your observations. Is the reaction reversible? When you
have finished, pour the liquid down the drain and wash the test tube with hot soapy water. If the
tube does not come clean, discard it into the blue broken glass waste container located in the
laboratory.
C.
CdCl2•3 H2O
There are two containers with CdCl2
3 H2O in the laboratory for you to observe. One is sealed from
the atmosphere, the other is open and exposed to the air. What difference do you observe between the
appearance of the crystals in the sealed and open containers? Record your observations.
D.
CaCl2
Again there are two containers of CaCl2 in the laboratory for you to observe. Observe the appearance
of the anhydrous CaCl2 that is in a sealed container and CaCl2 that has been exposed to the air for
several hours. What difference do you observe? Record your observations.
NOTE:
Before going on to Part III, remember to repeat the heating, cooling, and weighing of the
hydrate sample in Part I D until a constant mass is obtained.
