Science Buddies: "Ask an Expert"

I am doing the electrolyte challenge with my 3rd grader. We are testing orange juice vs gatorade. If the project is testing orange juice and gatorade, why are we also measuring the conductance of distilled water and tap water?

Hey there!

Great choice for a project to work on together. So--in answer to your question the conductivity of distilled and tap water are actually relevant in this experiment.

Distilled water is going to be what is known as a control. You should have zero conductivity with it, so this is what you are going to use to ensure the meter itself is set at a true zero before testing the other liquids. It is also there to use as a means to clean off the probes between liquid measurements.

The tap water works in much the same fashion--however, because it can register conductivity (due to trace mineral elements this can vary widely) it is there as sort of a "first rinse" bowl before using the distilled water. It is also there as a way to show what everyday water tap water itself can contain for potential benefits over say a cola.

Hope this helps. Please feel free to reach out again if other questions arise.

Elizabeth