PROCEDURE
1. Obtain and wear goggles! DANGER: Handle all the solutions in this experiment with care. They may be harmful if swallowed or in contact with the skin or eyes. Do not handle until all safety precautions have been understood Notify your teacher in the event of an accident.
2. Assemble the Conductivity Probe, utility clamp, and ring stand as shown in Figure 1. Be sure the probe is clean and dry before beginning the experiment.
3. Set the selector switch on the side of the Conductivity Probe to the 0–20000 µS/cm range. Connect the Conductivity Probe to LabQuest and choose New from the File menu. If you have an older sensor that does not auto-ID, manually set up the sensor.
4. Obtain the Group A solution containers. The solutions are: 0.05 M CaCl2, 0.05 M NaCl, and 0.05 M Fe(NO3)3.
Measure the conductivity of each of the solutions.
a. Carefully raise each vial and its contents up around the Conductivity Probe until the hole near the probe end is completely submerged in the solution being tested. Important: Since the two electrodes are positioned on either side of the hole, this part of the probe must be completely submerged.
b. Briefly swirl the vial contents. Monitor the conductivity reading displayed on the screen for 6–8 seconds, then record the value in your data table.
c. Before testing the next solution, clean the electrodes by surrounding them with a 250 mL beaker and rinse them with distilled water from a wash bottle. Blot the outside of the probe end dry using a tissue. It is not necessary to dry the inside of the hole near the probe end.
6. Obtain the four Group B solution containers. These include 0.05 M HC2H3O2, 0.05 M HCl,
0.05 M H3PO4, and 0.05 M H3BO3. Repeat the Step 5 procedure.
7. Obtain the five Group C solutions or liquids. These include distilled H2O, tap H2O, 0.05 M CH3OH, and 0.05 M C2H6O2. Repeat the Step 5 procedure.
DATA TABLE
Solution Conductivity (µS/cm)
A – CaCl2
A – Fe(NO3)3
A – NaCl
B – HC2H3O2
B – HCl
B – H3PO4
B – H3BO3
C – H2Odistilled
C – H2Otap
C – CH3OH
