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E-10
-
To the remaining 8 test tubes, add
the following reagents. Record a description
of each reagent
added on your Observations Sheet.
Allow the solutions to stand for
20 minutes to give time for equilibrium to be reestablished.
Compare the
colours of the solutions in test
tubes 2 to 9 to the reference colour in test tube 1. Record
a detailed
description of each solution on
your Observations Sheet.
reagent added
Test Tube 2
5 drops of 0.10 M
Fe(NO3)
3(aq)
Test Tube 3
5 drops of 0.020 M
KNCS
(aq)
Test Tube 4
5 drops of 6.0 M
NaOH
(aq)
Test Tube 5
5 drops
of 0.20 M NaF
(aq)
Test Tube 6
**2
drops of 0.20 M
Na2©2O
4(aq)
Test Tube 7
**1
drop of 0.10 M
K
4
[Fe(CN)
6
]
(aq)
Test Tube 8
**1
drop of 1.0 M
NH3
(aq)
Test Tube 9
5 drops
of 0.10 M AgNO3
(aq)
NOTES:
1.
To compare the colours of the solutions,
hold the test tubes over a white
tile and look
directly down at the solution from
above as
well as from the side.
2.
When you have finished recording
your
observations, pour all of the solutions
as well
as the first rinse of the test
tubes into the your
toxic waste beaker
Part II. Solubility of Lead
Salts
A.
Solubility Pb(NO3)2
and PbCl2 in solutions of varying chloride
concentrations.
1.
Using automatic dispensers, combine
0.5 mL of 1.0 M Pb(NO3)2
with 0.5 mL of 1.0 M NaCl in a
13 x 100 mm tube (test tube #1)
and mix thoroughly. What do you observe? Record your
observations. Add 3.0 mL
of deionized water (total volume is now approximately 8 mL) and mix
thoroughly. Set this test
tube aside to allow the precipitate settle.
2.
In this step, a reaction solution
will be prepared in which the initial concentration of HCl above the
PbCl
2(s)
is about 3.0 M.
Again, using the automatic dispensers, combine 0.5 mL of 1.0
M Pb(NO3)2,
with 0.5 mL of 1.0
M NaCl in a clean test tube. Add 2.0 mL of deionized water,
stir, and then add 1.0
mL of 12.4
M HCl to the test tube and mix thoroughly.
WARNING: 12.4 M HCl
is very corrosive.
Wash immediately if you get any
on your skin. Cover the test tube with parafilm
and mix well. Set
this test tube aside to allow the
precipitate to settle.
3.
In this step, a reaction solution
will be prepared in which the initial concentration of HCl above the
PbCl
2 (s)
is about 9.0 M.
Repeat the combining of 0.5 mL of 1.0 M Pb(NO3)2
with 0.5 mL of 1.0 M
NaCl in a clean test tube.
Add 3.0 mL of 12.4 M
HCl to the precipitate and mix thoroughly. Cover
the test tube with parafilm and
mix well. Allow the precipitate to settle. Record your observations.
