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The Concept
This experiment is useful in introducing the concept of pH. A simple explanation for younger grades can be that pH is a scale of how acidic something is. Point out common items that students are familiar with, such as soda, coffee, vinegar, baking soda and other cupboard items and have them guess if they are acidic or basic. A lesson for older students would show that pH is a measure of hydrogen ion activity.
Required Materials
The materials required for this experiment include water, fabric, vinegar, baking soda, nine cups, litmus paper, laundry detergent and a washing machine. It is helpful if the samples of fabric are all the same color, material and size. The cups should all be the same size. Baking powder can be substituted for baking soda if necessary.
Procedure
Prepare nine cups -- one cup for each pH value from four to 12, by mixing vinegar with water to create acidic solutions and baking soda with water to make basic solutions. Determine the pH level of each cup with litmus paper and make adjustments until the desired pH level is reached. This can be a lengthy process. Label each piece of cloth with a fabric marker then place one in each cup for one hour. Rinse them with water then put them in a washing machine for a regular cycle. Hang them to dry overnight.
Conclusion
If the experiment is successful, pieces of fabric placed in the very alkaline solutions will have faded the most, suggesting that high pH levels can make clothes age quicker. This can be a good introduction to how the characteristics of the water used in a washing machine can affect clothes. You can also ask students how they think waste water with high pH levels will affect the environment if dumped or released.