Ecology: Conductivity of Water

Find out what the conductivity of water tells you about water quality.

Motion Sensors

With probeware you are able to view pH and conductivity data simultaneously. As you manipulate variables, you can rapidly determine which variables cause significant changes in the water’s pH and conductivity. Enlarge graph.

Lab Summary:

The conductivity of water is an indication of the quality of water, along with other factors, such as pH, turbidity, presence of microorganisms, presence of organic chemicals, etc. Measurement of the conductivity of water gives a quick indication of the total dissolved solids (TDS) in the water.

Students will use a conductivity sensor to explore factors that contribute to higher conductivity of water. They will investigate the cause of higher conductivity by comparing the conductivity of increasing amounts of ionic substances (table salt and soluble fertilizer) and a nonionic substance (sugar) dissolved in water. Finally, students will explore how nutrients from the soil, such as fertilizers, can enter adjacent water supplies. They will construct a watershed model and determine how the application of fertilizer to the soil of the watershed affects the conductivity of the runoff water.

Download Free Lab  (PDF, 604 KB)

(student version)

Method:

Motion Sensors

Use the pH and Conductivity Sensors to measure the pH and
conductivity of a variety of water samples.

Here's What You Need

Probeware

Other Materials

  • Balance
  • Watering can or squeeze water bottle
  • Labels and Labeling Pens
  • Clean plastic bottles with screw tops
  • Beaker, 250-mL
  • Spatula
  • Large, flat, low-sided rectangular pan
  • Protective Gear
  • Weighing Paper
  • Water, 2.0 L
  • Soil or Sand sample, 2.0 kg
  • Table Salt (NaCl), 1.5 g
  • Water samples (from streams, etc.), 1.0 L ea
  • Water, Distilled, 2.0 L
  • Table Sugar (C6H12O6), 1.5 g
  • Soluble Fertilizer, 20.0 g

Lab Manual:

This activity is included in Explorations in Biology (PS-2807), complete with Teacher Information pages, student instructions and handouts, and sample data for a total of 25 probeware-based labs. For your convenience, we offer bundles which provide the probeware necessary for the activities in the manual. For more information on these resources and bundles, click here.