 |
 |
10 of 19 |  |
 |
 |
E-10
EXPERIMENTAL PROCEDURE
NOTE:
Some of the chemicals used in this experiment are
very toxic. Therefore these solutions must NOT
be poured down the drain. Label a large beaker TOXIC WASTE and keep it at your workstation so
that all toxic waste can be poured into it as you work through the experiment. At the end of the
laboratory session, pour the content of this beaker into the designated TOXIC WASTE container in
the fumehood.
Part I. The Iron(III) Thiocyanate Equilibrium
Using automatic dispensers, combine 1.0 mL of 0.050 M Fe(NO3)3 and 1.0 mL of 0.020 M KNCS in a 50 mL
graduated cylinder and dilute the solution by adding deionized water to the 20.0 mL mark. Pour the diluted
solution into a 50 mL beaker and mix the solution well. Transfer 2.0 mL of this solution into each of 9
different 13 x 100 mm test tubes.
Hint:
Measure 2.0 mL in a clean 10 mL graduated cylinder and transfer to test tube #1. Fill the remaining
8 test tubes to the same level
-
To test tube 1, add 5 drops of deionized H2O. This test tube provides a reference colour for
comparison with the other solutions. Record the colour of this solution on your Observations Sheet.
-
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.
NOTE:
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.
