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C-5
REAGENTS AND EQUIPMENT
hydrate samples (unknowns)
nichrome wire
Bunsen burner
6.0 M HCl
6.0 M HNO3
balances
1.0 M NaOH
1.0 M H2SO
4
test tubes
1.0 M BaCl2
0.10 M AgNO3
CuSO
4
•5 H2O (crystals)
NaCl (solid)
NaBr (solid)
sugar (sucrose: C
12
H
22
O
11
)
CdCl2•3 H2O
anhydrous CaCl2
EXPERIMENTAL PROCEDURE
Part I. Unknown Hydrate - Determination of the Percentage of Water
Remembered to put on your safety glasses
A.
Wash the medium test tube provided, rinse it with DI water then drain and dry the tube. Grip the test
tube with a small finger utility clamp and heat the test tube for about 5 minutes to thoroughly dry it. At
this point turn off the gas and place the test tube with the clamp inside a 400 mL beaker on the counter
to cool.
NOTE: Once the test tube has been cleaned in this manner, DO NOT touch the test tube again
with your fingers until you have finished the experiment.
B.
Obtain a hydrate sample from your laboratory instructor and record the code number on the
Observations Sheet. Read the label printed on the sample bottle and follow any special directions.
Describe the appearance of the hydrate on the Observations Sheet. Some of these samples
decompose on heating, or give off a lot of water. Check the behavior of your unknown by putting
a small sample (~about the size of a vitamin pill) into another small test tube, and heating it
gently with the flame from a Bunsen burner. Note how gentle heating affects the hydrate (e.g.
color change, splattering, etc.) and then heat the sample intensely to determine if the hydrate is
susceptible to thermal decomposition.
