pH Investigation

Note: A very basic look at pH and pH testing was done in the Stream Study lesson plan #7 (Water Quality) in the Our Rivers section. You may want to refer to this lesson prior to doing this one.

Objectives:

1. Students will be able to apply the procedure of pH testing to various liquids.
2. Students will be able to use their knowledge about pH measurement to determine pH levels of various liquids.
3. Students will be able to use the Scientific Method while investigation pH levels.

Materials Needed:

• Stewardship Worksheet # S-2 (pH worksheet)
• pH test strips
• test tubes or small bottles
• acidic liquids (e.g. lemon juice, vinegar)
• alkaline liquids (e.g.baking soda water, household ammonia)
• various waters and other liquids (e.g. tap water, swamp water, hot tub water, stream water, kool aid

Note: The above are suggestions. There may be other liquids that you prefer.

Activity:

Discuss with your class the definition of and the purpose for pH testing. Share the hows and whys these tests are done.

Review the Scientific Method with the class and how to use it to write up experiments.

Using pH paper and water from the tap demonstrate to the class how the process works. Go through the steps of the Scientific Method as you demonstrate. You may wish to record this on chart paper or the blackboard so the students have a template to use later.

Using the liquids you have decided upon (see materials list), set up different testing stations around the room. Hand out "Stewardship Worksheet # S-2 (pH worksheet)". Have students test the acidity of each source and chart their results on the worksheet.

After students have completed each station and have recorded their results, share as a class and discuss.