Skip Navigation
Button that takes you to back to the home page. Button that takes you to the teacher pages. Button that takes you to the modules and activities page. Button that takes you to the related links page. Button that takes you to the references page. Button that takes you to the Problem Based Learning model page. Button that takes you to the glossary page.Image map of some Water Quality puzzle pieces.  Please have someone assist you with this.

Button that takes you to the Overview page.
Button that takes you to the Biological Assessment page.
Button that takes you to the Chemical Assessment page. Button that takes you to the pH page. Button that takes you to the Alkalinity page. Button that takes you to the Hardness page. Button that takes you to the Nitrates, Nitrites, and Ammonia page. Button that takes you to the Ortho-and Total Phosphate page. Button that takes you to the Dissolved Oxygen and Biochemical Oxygen Demand page. Button that takes you to the Fecal Coliform page. Image that says Conductivity and Density.
Button that takes you to the Physical Assessment page.

Water Quality Assessment: Chemical: Conductivity and Density
Conductivity is the ability of water to carry an electrical current. It indicates the physical presence of dissolved chemicals in the water. For example, when sodium chloride (NaCl, table salt) dissolves in water, it dissociates into Na+ and Cl- ions. The movement of these ions conducts electricity through the water. The dissociation of naturally-occurring, inorganic compounds is the main source of ions in stream water. Conductivity can also increase as a result of heavy metal ions released from pollutants such as acid mine drainage.

To "see" the electrical current being carried by Na+ and Cl- ions, try the following activity. First, connect the positive terminal of a battery to an electrode. Place the electrode in a glass of deionized water. Next, connect the negative terminal of the battery to a light bulb, then connect the light bulb to an electrode. Place the electrode in a glass of deionized water (see animation below). Notice that the light bulb does not glow. Add some salt (NaCl) to the deionized water (see animation below). Notice that the light bulb starts to glow. That is because the Na+ and Cl- ions complete the circuit between the positive and negative electrodes. They enable the electrical current to flow through the circuit.

Image showing the difference of a battery connected to deionized water without salt and deionized water with salt.  Please have someone assist you with this.

Like conductivity, water density is an indicator of the physical presence of chemicals in water. The density of water is related to salt content and water temperature. This is a very useful parameter to measure because the salinity of a body of water is one of the main factors determining what organisms will be found there.

 

Overview ..|.. Biological Assessment ..|.. Chemical Assessment ..|.. Physical Assessment.

pH / Alkalinity / Hardness / Nitrates. Nitrites, and Ammonia / Ortho- and Total Phosphate / Dissolved Oxygen and Biochemical Oxygen Demand / Fecal Coliform / Conductivity and Density
Glossary  .|
Related Links  .|.. References ..|.. PBL Model  .|

  Home ..|.. Teacher Pages ..|.. Modules & Activities  

Button that takes you back to the Water Quality main page.

HTML code by Chris Kreger
Maintained by ETE Team
Last updated November 10, 2004

Some images 2004 www.clipart.com

Privacy Statement and Copyright 1997-2004 by Wheeling Jesuit University/NASA-supported Classroom of the Future. All rights reserved.

Center for Educational Technologies, Circuit Board/Apple graphic logo, and COTF Classroom of the Future logo are registered trademarks of Wheeling Jesuit University.