CONDUCTIVITY OF SOLUTIONS
This lab simulates the dissertation of Arrhenius.
- Classify solutions as conductors and nonconductors.
- Determine the conductivity of two solutions serially diluted by two, twelve times.
- Determine and plot the conductivity as a function of concentration with four conducting solutions.
- Predict and determine the conductivity of a mixture of two solutions.
- Follow the instructor's demonstration on how to use and care for the 9 volt LED conductivity apparatus.
- You will find 10 to 15 solutions of liquids to test. Using a beral pipet put about 2 ml of each chemical in the well of the microplate. Determine if the chemical is a conductor, weak conductor, or non conductor.
Data Table: Record chemical and concentration
|Conductors ||Weak Conductors
- Collect the "multimeter" to measure a conduction in microamps, wires, and copper electrodes. Set up the apparatus as demonstrated by your teacher
- Collect 12 beakers (or scale down amounts appropiate for a microplate) and 20 ml of a 6 M concentration of an electrolyte.
- Set up the beakers in a row, on scrap paper maked as the data table indicates. Pour 10.0 ml of the electrolyte in the first beaker marked 6 M.
- Pour the other 10 ml of your electrolyte in the second beaker, add 10 ml of distilled water and stir. Pour 10 ml from beaker #2 (3M) and pour in beaker #3. Continue this serial dilution by two until you have a set of 12 beakers with the concentrations as the data table indicates.
- Tape the copper strips used as electrodes to a test tube or pencil to keep the distance constant. Set the meter to measure micro amps and measure the conductivity in each beaker. Record data and plot data.
- As time allows, serially dilute another electrolyte and measure the conductivity. Share and compare your data.
Data Table: Record conductivities for a given chemical:
|Electrolyte||Concentration of Solution (Molarity)|
| 6.0 || 3.0 || 1.5 || 0.8 || 0.4 || 0.2 || 0.1 ||0.05||0.02||0.01||0.005||0.000|
Select two solutions of 0.5 M concentration for which you have data on their conduction. Mix 10 ml of each solution in a beaker. Before you test conductivity, predict what the conductivity will be for the mixture. Explain the logic of your hypothesis.
Discussion of Results:
- How do you evaluate your precision and accuracy? You may have to get some class data to help with this.
- Present an argument using your own data or with the class data to support the following statements:
- "conductivity is proportional to concentation" .
- "conductivity of a mixture is the sum of the individual solution's conductivities".
Woodrow Wilson Leadership Program in Chemistry
The Woodrow Wilson National Fellowship Foundation
CN 5281, Princeton NJ 08543-5281