Vernier Software and Technology
Vernier Software & Technology

Effects of Concentration on Conductivity Using Go Direct® Conductivity

Join our Chemistry Staff Scientist, Melissa Hill, PhD, as she monitors conductivity while increasing the concentration of a solution by adding sodium chloride. Data is wirelessly collected and analyzed using our Go Direct Conductivity and free Graphical Analysis™ 4 app.

In this video, we will be investigating the effect concentration has on the conductivity of solutions. If an ionic compound is dissolved in water, it dissociates into ions and the resulting solution will conduct electricity. This can be measured with our Go Direct™ Conductivity Probe. Conductivity will be measured as the concentration of the solution is gradually increased by the addition of concentrated drops of three different salts: sodium chloride, aluminum chloride and calcium chloride.

The Go Direct™ Conductivity Sensor can be connected via USB or via Bluetooth to your platform. The platform can be a Chromebook, Mac computer, Windows computer, IOS, or Android device. To get started, make sure you have downloaded the Free Graphical Analysis™ 4 app from our website or the appropriate app store. Since I will be taking data via Bluetooth, I'll first turn on my conductivity probe. Then I will launch the Graphical Analysis™ 4 software and select Sensor Data Collection. I then connect my conductivity probe and select 'Done'.

For this experiment, I want to be able to tell the software how many drops of ionic solution I have added. This requires a mode we call "Events With Entry." To set up my data collection, I will tap on the Mode button and then, from the Mode Drop-Down Menu, select 'Event Based'. 'Events With Entry' is selected by default. I will re-name the event 'Volume' and put the units in 'Drops'. Then press 'Done'. I'm now ready to start data by pressing the 'collect' button. No data points will be recorded until I press 'Keep'.

My conductivity probe is currently in distilled water and my live conductivity reading is here and stable. I want to take a zero data point, so I will go ahead and press 'Keep'. Now it will ask me how many drops of solution I have added. Type in zero drops. Then press 'Keep Point'. Now I will add one drop of sodium chloride solution and make sure the solution is mixing. I will monitor the conductivity reading until it's stable. Then select 'Keep' and type one drop. I want to repeat this process for about five drops. That's my second drop. Tap 'Keep'. Two drops. This is my third drop. Press 'Keep'. Four drops. And my last drop. Five. Now I will stop data collection. Now I will analyze this data by clicking on the Graph Tools icon and selecting 'Apply Curve Fit'. I would like the Linear Curve Fit, so I tap anywhere on the graph to display the parameters and I want to record the slope of the line, which in this case is 89.7. I will repeat this process for my other two ionic solutions, calcium chloride and aluminum chloride, and compare the slopes for all three solutions.

For more information about the Vernier Go Direct™ Conductivity Probe, and our entire line of Go Direct™ sensors, visit our website or email

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