Conductivity is a measure of the ability of a substance
to conduct an electrical current. A solution’s conductivity
is affected by the presence of inorganic dissolved salts such as
chloride, nitrate, sulfate, and phosphate anions (negatively-charged
ions) or sodium, magnesium, calcium, iron, and aluminum cations
(positively-charged ions). Organic compounds like oil, phenol, alcohol,
and sugar do not conduct electrical current very well and therefore
have a low conductivity when in aqueous solution. Because conductivity
is dependent upon solute concentration, conductivity measurements
are a good indication of the concentration of dissolved solids in
aqueous solution. Conductivity is also affected by temperature:
the warmer the solution, the higher the conductivity.
In natural settings, salt content may be high in both
soil and water. River waters, for example, show a wide range of
salinities due to different soil types, geological structures, and
the extent to which they are influenced by inflows of saline groundwater.
Problems arise when the natural balance of salinity in the landscape
changes. Salinity is a major threat to surface and groundwater resources.
Depending on the level of salt content in soil, plant growth may
be impacted. High levels of salinity in rivers may limit water use
for irrigation, agriculture, stock watering and domestic water supplies.
Salinity can also affect freshwater aquatic flora, fauna and riparian
vegetation. In urban areas, salinity reduces the lifespan of domestic
and industrial equipment, leading to higher maintenance costs and
greater use of cleaning products.
For aqueous solutions, the most commonly used units
of measurement for conductivity are microsiemens/centimeter (µS/cm)
and millisiemens/centimeter (mS/cm). See "Teacher’s Hints"
for more information about these standard units.
)
of the Conductivity Sensor.
) to begin collecting data. Because the pre-configured DataStudio
file has been prepared for manual sampling, the Start button will
change to a Keep ( 
) button.
) of
the Keep button to end the experiment.
) in the Graph toolbar to resize the axes.
) in the Graph toolbar and look for the minimum and maximum values
to appear in the graph legend.
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