Austin Middle School 7th grade Science Mr. McFarland Mrs. Yarbrough

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Austin Middle School7th grade ScienceMr.
McFarlandMrs. Yarbrough
Environmental water testing with Karen Siddall
City of Irving Storm Water Coordinator and
Lisa Mensing-City of Irving Water Quality
Inspector
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Students use the same water test kits used by
Texas Watch volunteers who monitor the waters
of Texas. Kits were provided by the City of
Irving and UT Arlington.
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Students first obtain a sample of water that Mr.
McFarland collected during a recent rain. The
samples included water from a nearby creek, roof
runoff, and water from a fish tank aquarium.
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Students pour a water sample from a creek into
the vile to begin the process of testing pH.
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Students add a wide range indicator to the water
sample.
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Once the wide range indicator has been carefully
added, the vile is gently rocked back and forth
to mix the solution. The vial is then inserted
into the pH comparators.
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This student places a white piece of paper behind
the pH comparator so he can determine the correct
pH of his water sample.
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By comparing the color of the water sample to the
color of the viles in the pH kit, this student
determines that the pH is between 7.0 and 7.5.
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Using the LeMotte kits, one can determine whether
the water is acid (top scale) or alkaline (bottom
scale)
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Lisa Mensing from the City of Irving Water
Utilities, helps students determine the correct
pH.
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Karen Siddall, City of Irving Storm water
Coordinator, helps students learn to use a
conductivity meter which determines the quantity
of solids in the water.
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By using the conductivity meters, students found
that rainwater off the roof was 40, creek water
was 130, and aquarium water was 700.
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This student is determining how much dissolved
oxygen is in the water sample. She first adds
Manganous Sulfate and Potassium Hydroxide to the
water sample to form a precipitate.
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The precipitate (Manganic Hydroxide) can be seen
as the rusty brown matter settling to the bottom
of the jar.
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These students shake the sample bottles to make
sure all of the chemicals are mixed thoroughly.
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These students add Sulfuric Acid to the sample to
dissolve the precipitate.
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Students then take some of the fixed sample
from the bottle and pour 15 ml into a cylinder so
that they may begin the titration.
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This student fills the titration syringe with
Sodium Thiosulfate so he may add it to the sample
solution.
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Once the water sample turns almost clear, a
starch indicator solution is added and the sample
turns a dark blue.
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Once the starch indicator has been added and
stirred, more Sodium Thiosulfate is added just
until the solution turns clear. The students
then determine how many milliliters of solution
was added, which corresponds to the amount of
dissolved oxygen in the water being tested.
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These tests of water quality, performed in the
classroom, help raise students awareness of
water, the environment, and the effects of
pollution. With further studies in class,
students will see how important water is, how
biomes and ecosystems rely on water, and learn
ways in which to protect Earths important
resources.

created by John McFarland