 |
 |
1 of 14 |  |
 |
 |
A-1
EXPERIMENT A: PREPARATION OF COPPER(II)
SULFATE
OBJECTIVES
In Experiments A and B, you will investigate
the chemical reactivity of copper via the preparation of a few
of its ionic compounds. You will be
introduced to some of the experimental techniques and procedures
used in the chemistry laboratory.
In Experiment A, you will prepare copper(II) sulfate starting with copper
metal. You will let the copper(II)
sulfate crystallize until next week. This copper(II) sulfate will
be used as
the starting material for further reactions
in Experiment B.
THEORETICAL CONSIDERATIONS
You will prepare a series of compounds of
copper starting from metallic copper. Although copper can exist
as either copper(I) or as copper(II), only
the more stable Cu
2+
ion will be studied in Experiments A and
B.
The copper compounds that you will prepare
will vary considerably in characteristics such as color,
solubility, and crystal type. These
differences illustrate the complexity and intricacy of chemical reactions.
You will observe the differences between
the compounds you synthesize. As the cation is the same (Cu
2+
)
in each case, any differences can be attributed
to the anion(s) or ligands bonded to the Cu
2+
ion. A ligand is
a neutral molecule or ion having a lone
pair of electrons that can be used to form a bond to a metal ion.
Copper does not readily react with sulfuric
or hydrochloric acids. However, copper does react with nitric
acid (HNO3),
a strong oxidizing agent, and forms copper(II) nitrate. Copper(II)
nitrate is very soluble in
water.
The reaction scheme that you will follow
in this experiment is shown below:
Cu
(s)
Cu(NO3)
2(aq)
CuCO
3(s)
??CuSO
4(aq)
One of the products of the reaction of nitric
acid with copper is nitrogen monoxide (NO) which is a
colorless gas. On exposure to air,
this gas immediately reacts with oxygen to form the poisonous
reddish
brown gas, nitrogen dioxide (NO2).
As a consequence, you must carry out this reaction
in the fume
hood.
