Use the strips to test the acidity/alkalinity of various solutions around your house. For example:
Lemon juice, vinegar
Orange juice, soda
Tomato juice, acid rain
Black coffee, bananas
Milk, saliva
Pure water
Sea water, eggs
Baking soda solution
Milk of magnesia
Ammonia solution
Soapy water
Note: if you test the pH of saliva, do not put the pH paper in your mouth! Instead, spit some saliva into a clean container and dip the paper into the saliva.
After testing, put the pH strips in order of increasing pH of the solution tested.
You can use the table in the Introduction as a guide.
The Variations section has some additional suggestions for independent confirmations of the pH readings.
Do you see a gradual change in color as the pH of the tested solutions varies? Can you match specific colors to certain pH levels? Over what range of pH does the color continue to change? How accurately do you think you can determine the pH of a solution with your test papers? Within 1, 2, or 3 pH units?