This activity is meant to prepare students to do the full-length Conductivity Lab.
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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.

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I created a Google Doc for students this year (2024) so they would have an easier time writing down their answers. I used the following questions to guide them:

Lab: Exploring Conductivity

Responses:

1. What is your procedure for measuring the conductivity of water and distilled water? What measurements did you record?
2. Electronic meters do not have a physical zero marking and may need adjustments to read zero. But distilled water is water with zero electrolytes. How could you use this fact to decide what measurement with the conductivity meter is actually zero?
3. Which liquid contained a dissolved electrolyte, the tap water or the distilled water? How do you know?
4. Describe what you have to do with the software that controls the conductivity meter in order to make measurements of conductivity vs. the amount of salt added.
5. Describe how to set up the graph on the screen so that the maximum number of portions of added salt is 12.
6. What would a student first learning how to use the conductivity probe need to know so they can use it successfully?
7. Copy and paste your graph from the software into the space below. It must show the portions of salt on the x-axis and the conductivity on the y-axis.
8. Is there a direct or inverse proportion between the amount of salt added and the conductivity? Give evidence for your answer using a description of the graph of your data.
9. Look at the data on the graph and use it to decide whether all of the portions of salt in your procedure were the same size. Were they? How do you know? Use your graph as evidence.
After doing this activity, go ahead and do the Conductivity Lab.
Last updated: Mar 12, 2024       Home