Bio 413 Ph Lab Task Handout

BIO 413 pH Lab Task Introduction The numerical scale called pH indicates how acidic or basic an aqueous (water) solution is, or whether that solution is neutral. Many products we use daily for personal hygiene, home and auto care, or eating and drinking are suitable for pH testing. Purpose To determine the pH of common household products and classify each based on its acidic or basic properties using the pH scale. Safety Wear protective goggles at all times. Avoid skin contact with solids and solutions. Dispose of all solutions in the containers provided by your teacher. Wash your hands before leaving the laboratory. Procedure Before you begin you must construct a data table. Include the sample name, appearance, pH paper color and pH value. 1. Obtain several small strips of wide-range pHydrion paper. 2. Set up data table and key of substances before you begin. 3. Set up an area for temporarily discarding the used test papers. (Not the sink!) 4. Using the pH paper. Transfer a few drops of the product to be tested to a spot plate. Transfer the pH paper using tongs or tweezers. 5. Observe the color change. Then match the final color to those on the chart to determine the pH value of the product. 8. Record the pH of each product. 9. Rinse the spot plates and put used pH papers in trash. 10. Clean up all materials. Return goggles and wash hands thoroughly before leaving the laboratory.

BIO 413 pH Lab Task Questions

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What is pH? Why is pH important to living organisms? How is pH measured? Explain what happens to a water molecule when “stuff” is added. Predict what the pH of rain water would be and explain your answer. What pH value or range of values is/are considered: acidic, alkaline or neutral? What word describes the property of water that is responsible for the formation of acids & bases? 8. What ion or part of a water molecule is associated with an acid? 9. Consider why pH would be important to a biologist—be specific.