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How does the acidity of lake water affect the hardness of Zebra mussel shells? Featured science projectScience project video


The materials required for this science fair project:

-    10 Zebra mussels from a lake with water at approximately pH6.5
-    10 Zebra mussels from a lake with water at approximatelypH7.0
-    10 Zebra mussels from a lake with water at approximately pH7.5
-    You may need to enlist the help of an adult who can provide you with transport to lakes in the vicinity of where you live.
-    A knife
-    A manual hardness tester - check with your school's science laboratory if they have either manual or electric hardness testers
-    Sufficient quantities of pH paper
-    3 plastic containers
-    A black marker pen


1.    For this science fair project, the independent variable is the acidity of the lakes from which the Zebra mussels are harvested i.e. pH 6.5, pH7.0 and pH 7.5. The dependent variable is the hardness of the mussel shells. This is determined by using the manual hardness tester to check the hardness of the shell. The constants (control variables) are the age of the Zebra mussel, the amount of calcium in the water and the climate or temperature at the lakes.

2.    The location of 3 lakes which contain Zebra mussels and are of different pH levels are selected. The preferred pH levels of the water in the lakes are pH 6.5 (acidic), 7.0 (neutral) and 7.5 (alkaline). A trip is made to the 3 lakes and their pH levels verified by testing the waters from the lake. 10 Zebra mussels are obtained from each lake and brought back to the lab for the remainder of the science fair project.

3.    3 plastic containers are labeled “pH 6.5”, “pH 7.0” and “pH 7.5”. The contents of the zebra mussel are removed from the shell. Wash the shells and placed inside the plastic containers according to the pH level markings of the lakes from which they were obtained.

4.    The manual hardness tester is used to check the hardness of the shells. The average hardness for the 10 shells from each lake is recorded and the results recorded in the table below.

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Complexity level:
Project cost ($):
Time required:
1 day to prepare, 1 day for observation
Material availability:
You will need access to a hardness tester. You will also require transportation to travel to the lakes to gather mussel samples
Safety concerns:

Basic safety requirements