PASCO CI-6729 (1X) CONDUCTIVITY SENSOR - Manual (Page 23)

19
012–06485B Conductivity Sensor
Teacher’s Notes
These experiments are designed to familiarize the student with the operation of the Conductivity
Sensor. In addition, these experiments illustrate various factors that affect sensor readings. We
recommend that the experiments are performed in order, with the student building on the
information from previous experiments.
Notes on Experiment 1
1. This experiment is designed to familiarize students with the basic operations of the
Conductivity Sensor, and the effects of impurities on water samples. In addition to the
water samples listed in this experiment, students can carry out ecological investigations by
measuring the conductivity of water samples taken from streams, ponds, lakes or the ocean.
The student can calibrate the sensor (as described on page 6 and 7) if very accurate
measurements are desirable.
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Students will need access to pages 6–7 of the manual.
Below are some sample data. The bottled water was Crystal Geyser and the mineral water was
Perrier.
κ(distilled or deionized H
2
O) = ________ µS/cm
κ(tap H
2
O) = ________ µS/cm
κ(bottled H
2
O) = ________ µS/cm
κ(mineral H
2
O) = ________ µS/cm
Data Analysis
TDS distilled or deionized H
2
O = __________ ppm TDS tap H
2
O = __________ ppm
TDS bottled =__________ ppm TDS mineral = __________ ppm
Answers to questions
1. The mineral water should have the highest levels of impurities in it.
2. Since temperature is related to the velocity of the ions in the solutions, change in temperature
will affect the transport of electric charges in the solution, resulting in a change in the
conductivity of the solution.
Notes on Experiment 2
It is assumed that the student has completed experiment 1 before carrying out this experiment.
Students must keep stirring the solution until all crystals have been dissolved before each
conductivity measurement. As the concentration increases the amount of time required to stir
4 70
148 747
2 35
374 74