Kinetic Molecular Theory Gas Laws - Oakland Schools

Sources
Holt Chemfile C Inquiry Experiment Modern Chemistry 2004 Holt, Rinehart, and Winston
Procedure/Description of Lesson
Situation
The company you work for has been hired as an expert witness in a lawsuit. The local
chapter of Bass Anglers Unlimited has been disturbed by recent declines in the
population of bass in Pulaski Lake. There have been several fish kills, in which large
numbers of fish have died at the same time and floated to the surface of the lake,
creating a terrible smell and fouling the water. The anglers claim that the fish kills
begin shortly after the R. C. Throckmorton Power Plant came on line, and they are
seeking a court order to shut down the plant. The machinery in the power plant uses
water from the lake as a coolant and then returns the water to the lake.
The anglers say that something in the returned water is killing the fish. The utility
company operating the power plant points out that they use a closed system that
prevents the water from coming into direct contact wit the machinery in the plant.
They say that the water is just as pure when it comes out as when it goes in; it’s just a
little warmer. The court has asked you to investigate whether there is a scientific basis
for the anglers’ claim.
Background
Fish rely on the oxygen dissolved in water to live. The water passes through their gills,
which remove the oxygen. The less oxygen in the water, the harder the gills have to
work to get enough oxygen to keep the fish alive. The normal lake temperature is
between 15oC and 17oC. Another witness, a biology professor specializing in
ichthyology (the study of fish), has testified that if the oxygen content of the water dips
below 90% of the normal value at these temperatures or rises above 113% the normal
value at these temperatures, the fish will suffer long-term damage or death. The
temperature of the water returned to the lake from the power plant is 28oC. To
measure the change in dissolved-oxygen content over this temperature range, you can
use tap water, which has a mineral content similar to that of lake water.
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