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. 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 5 until all unknown substances have been tested. Explain how you reached your hypothesis.