Record hypothesis of substance name and pH number on the Observation Sheet. Do the same for all of the substances. Review with students the proper procedure of smelling unknown substances. Placing the container 6 inches from the nose, hold hand above the container and wave odor toward yourself. Never smell an unknown substance directly from the container.
Many liquids are toxic if inhaled directly, such as some cleaning substances.
Take a strip of pH paper and dip it into the unknown substance. 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.