NUMBAT OER - Open Educational Resources

7. pH

In various areas of chemistry and physiology, you will come across the units of pH. These are a measure of acidity and are a special case of logarithms. The letter p is used to denote the expression -log10. H denotes hydrogen ion concentration, or [H+], in mol l-1 so that pH actually means: -log10[H+].

pH runs from 0 to 14 so that a pH of 2 has a concentration of hydrogen ions of 10-2 mol-1 which is very acidic, a pH of 7 has a concentration of hydrogen ions of 10-7 mol-1 which is considered neutral whereas a pH of 13 has a concentration of hydrogen ions of 10-13 mol-1 which is very alkaline.

Find out more (perhaps more than you want!) at http://en.wikipedia.org/wiki/PH

An easier introduction can be found at http://www.johnkyrk.com/pH.html

Try out this interactive pH scale at http://www.purchon.com/chemistry/flash/ph.swf