5D30.10 - Conductivity of Water

Code Number:
Demo Title:
Conductivity of Water
Solution Conductivity
Area of Study:
Electricity and Magnetism
Battery Jars (2), Carbon Electrodes on Plastic Support, Switch, Light bulb, Power Cord, Salt, Acid (Hydrochloric, Sulfuric), and Stirring Rod, Conductivity Probe (homemade).

Place water that has been run through the filters into the battery jars so that the electrodes are sufficiently submerged. There should be no observed conductivity as shown with the light bulb. Pour in salt and the light will start to glow. This will take a lot of salt as it takes time for the salt to dissolve and diffuse. For this reason the acid may be the better choice in some cases as this problem does not occur.

The homemade conductivity probe can be used to observe the effect of ion concentration to conductivity in solutions.

Caution: Avoid acid burns and always unplug the power when moving the electrodes.

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  • Ef-1:  Freier and Anderson,  A Demonstration Handbook for Physics.
  • E-260:  "Pigtail Socket - Salt Solution",  DICK and RAE Physics Demo Notebook.
  • Bassam Z. Shakhashiri, "9.31 - Electrical Conductivity of Liquids", Chemical Demonstrations, Vol. 3, p. 326.
  • 70:  "Electrolytic Titration", Chemical Demonstrations, Vol. 2, p. 132.
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  • Bobby Mercer, "Energy Drink Tester", Junk Drawer Chemistry, 2016, p. 110.
  • W. Bolton, "The Electrical Conductivity of Sodium Chloride", Book 4 - Electricity, Physics Experiments and Projects, 1968, p. 9-10.
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  • Borislaw Bilash II, “Electrolytes and Nonelectrolytes“, A Demo A Day – A Year of Physical Science Demonstrations, p. 173.

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