Objectives:

1. Classify solutions as conductors and nonconductors.
2. Determine the conductivity of two solutions serially diluted by two, twelve times.
3. Determine and plot the conductivity as a function of concentration with four conducting solutions.
4. Predict and determine the conductivity of a mixture of two solutions.

Procedure:

1. Follow the instructor's demonstration on how to use and care for the 9 volt LED conductivity apparatus.
2. 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

Part II

1. Collect the "multimeter" to measure a conduction in microamps, wires, and copper electrodes. Set up the apparatus as demonstrated by your teacher
2. Collect 12 beakers (or scale down amounts appropiate for a microplate) and 20 ml of a 6 M concentration of an electrolyte.
3. 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.
4. 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.
5. 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.
6. As time allows, serially dilute another electrolyte and measure the conductivity. Share and compare your data.

Data Table: Record conductivities for a given chemical:

Part III

Discussion of Results:

1. How do you evaluate your precision and accuracy? You may have to get some class data to help with this.
2. 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".

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