Lab: Exploring Conductivity

In this brief activity you will learn how to use the Vernier Conductivity Probe and the Graphical Analysis Chromebook app used to collect data using the probe.

An ionic compound in the act of dissolving in water.

1. Create a Google Doc in which to write your answers to the questions embedded in this lab activity’s instructions.
2. Figure out how to measure the conductivity of 100 mL of tap water and 100 mL of distilled water with a sensitivity setting of 0 - 200.
   1. What are you going to do to avoid cross-contamination?
   2. In your Doc as Response no. 1, write down your procedure and record your numerical results.
   3. Consider whether the probe is guaranteed to read zero conductivity when there are no ions dissolved in the water. In your Doc as Response no. 2, write down how you would determine what value for conductivity represents zero conductivity.
   4. Response no. 3: If only one of the two liquids contains a dissolved electrolyte, then which one do you think it is? Why?
3. Shortly you will be asked to take data in which you measure the conductivity of solutions with different amounts of salt added to them.
   1. Figure out how to take data for conductivity versus the amount of salt added. Set up the software and write in Doc how to do it as Response no. 4.
   2. Figure out how to set up the graph axis so that the maximum number of portions of salt added is 12. Do so and then describe how to set it in your doc as Response no. 5.
4. Set the sensitivity on the sensor to 0 - 20,000. Figure out the relationship between the number of portions of salt and the conductivity. Do this by creating a graph of portions vs. conductivity. First, stir the beaker of 100 mL of distilled water (from earlier) with a glass stirring rod. Second, get a tiny bit of salt on the wet stirring rod (just enough to cover the end) then mix it with the water. Third, when you judge that the time is right “Keep” the data point and enter the number of portions you have added so far. Collect data for 10 - 12 portions with a sensitivity of 0 - 20,000.
   1. Write down in your Doc 2 or 3 pieces of advice for a student who is learning how to use this probe and this software as Response no. 6.
   2. Copy and paste your completed graph into your Doc as Response no. 7.
   3. Response no. 8: What kind of proportion exists between the portions of salt and the measured conductivity of the solution? Give evidence for your answer.
   4. Response no. 9: Were all of your portions the same size? How do you know? Use your graph as evidence.