Lab 3073
Understanding Water pH
Melissa M. Fowler
Understanding Water pH
Purpose
Students will be able to:
1. Identify 3 reasons for pH testing
2. Understand the pH scale
3. Test water for pH
Materials
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Water
Lemon juice
Powdered lime
Litmus paper
pH scale handout
“Water pH” data sheet
pH test kit
pH meter or pen
7 styrofoam cups
Teacher Preparation
1.
Fill cups approximately 3/4 full with water.
2.
Label the bottom of three cups with 1L, 3L, and 5L. Add 1 tablespoon, 3
tablespoons, and 5 tablespoons lemon juice to the cups as labeled.
3.
Label the bottom of three cups with 1P, 3P, and 5P. Add 1 tablespoon, 3
tablespoons, and 5 tablespoons powdered lime to the cups as labeled. Make sure
the lime is stirred in well.
4.
Leave one cup to hold plain water.
5.
Label the sides of the cups with numbers 1-7. Mix up the cups so that not all of
the lemon juice or not all of the powdered lime cups are clumped together.
Procedure
1.
Explain how to use each of the testing methods to the students, including how to
determine the results.
2.
Have each pair of students then begin to test the water samples. Each pair should
each test all three samples with all three tests and record the data on the “Water
pH” data sheet.
3.
Create a class data table to compare all of the data. As a class fill in the results
table on the “Water pH” data sheet. This will help eliminate testing errors in the
data.
Discussion
1.
What is the proper pH for aquaculture tanks?
2.
Which cup is closest to the proper pH level for aquaculture tanks?
3.
Why is it important to test and manage the pH for our aquaculture crop?
4.
What other factors should we test for in the aquaculture tanks?
Name:_______________________
Water pH Data Sheet
Cup Number
Litmus paper color
pH test kit result
pH meter or pen
result
1
2
3
4
5
6
7
Results
Cup Number
1
2
3
4
Acid or Base
x
x
x
x
x
Cup Number
5
6
7
Acid or Base