About pH
 
    pH is a measurement of the hydrogen ion activity in a solution. 

    The pH measurements ranges from: 
     

      • pH of   0 - extremely acidic 
      • pH of   7 - neutral, neither acidic or basic 
      • pH of 14 - extremely basic. 

    Most living things do best in environments which are nearly neutral. If you have an aquarium or swimming pool you may be familiar with adjusting their pH..  

    In chemistry many reactions are sensitive to pH, and there are many substances which will not dissolve in neutral solutions but which will dissolve in acids or bases. 

 
 
 
 
Measuring pH

There are a number of methods for measuring the pH of a liquid. 

1. The least costly method for measuring pH is with a cabbage indicator. 
    You can make this in your kitchen using this recipe. 

2. A commercially available indicator solution is phenolphalein, which is obtainable from chemical suppliers. 
    Indicator solutions are often used for acid/base titrations. 

3. pH indicator papers are a method of measuring pH where pH of an unknown solution is  measured directly 
    by dipping the paper into the solution. 

pH indicator paper is available at pet stores, in the aquarium section, at swimming pool supply stores, and from science suppliers. The papers available at pet stores and swimming pool supply stores are designed to be very sensitive in small ranges around pH 7.  Science supply stores will have pH paper covering the range 1 to 14. 

5. A pH meter can be used for high precision measurements. These are relatively expensive ($100.00 or more) and take some care in use. These precision meters are not often used for elementary science fair projects. 
 
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