Environmental Science 430

Fall 1999

Lab #1: Water pH

Purpose: To measure pH of French Creek using different pH meters. Investigate precision, accuracy, and sampling.

Materials (number of meters in parentheses):

• pHep 2 meters (5)
• pHTestr 1 (3)
• Corning PS 15 (2)
• pHydrion Papers
• Orion Research model 211/digital pH meter (1)
• LaMotte Wide Range pH test kit (1)

Procedure:

1. Work in groups of three or four.
2. Measure and record the pH of French Creek using every type of meter.
3. Where multiple meters are available, measure the pH using different meters of the same type.
4. Have each person in your group take a measurement.

Due: One week from the beginning of your lab section. Submit your results and answers to the following questions.

Reminders: Answers must be typed, and calculations presented, even when not asked for explicitly in the questions, and late papers will not be accepted.

Questions:

1. (10 points) What is the average of pH 5.0 and pH 7.0? Show your calculations.
2. (10 points) Which method is most accurate? Which method is most precise?
3. (10 points) In what ways is taking an average appropriate? Inappropriate?
4. (10 points) What is the real pH of the stream?

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