Remove and observe paper color. Match the color on the strip of paper with pH color scale and record the pH number on Observation Sheet. Continue step 6 until all unknown substances have been tested. Do research in the surrounding area, at or near the location of a sewage treatment plant, or on ocean current charts, conduct a discussion with local scientists, chamber of commerce or a local environmental group. Students should explain the basis of their hypothesis and why or why not their guesses were close or not.
Any answer is acceptable as long as the student fully explains their reasoning.
Discuss pH background and pH color scale. Observe the first unknown substance and record its color, thickness, and smell. Record hypothesis of substance name and pH number on the Observation Sheet. Do the same for all of the substances. Use the proper procedure of smelling unknown substances by placing the container 6 inches from your nose, hold hand above the container and wave odor toward yourself.