Water properties: The pH Scale
No, you don't often hear your local news broadcaster say "Folks, today's pH value of
Dryville Creek is 6.3"! But pH is an important measurement of water. Maybe for a
science project you have taken the pH of water samples in your chemistry class ... and
here at the U.S. Geological Survey we take a pH measurement whenever water is studied.
Not only does the pH of a stream affect organisms living in the water, a changing pH in a
stream can be an indicator of increasing pollution or some other environmental factor.
Acids tend to have a sour taste (vinegar, for example, contains ethanoic acid, and lemon
juice contains citric acid). By the way, tasting unknown chemicals in order to try and
identify them is an extremely dangerous practice, and should NEVER be carried out!
Acids which are commonly found in the laboratory are hydrochloric acid, HCl, nitric
acid, and sulphuric acid.
Many bases have a soapy feel. Beware of strong ones, such as sodium hydroxide, as
these substances can cause serious damage to the skin. Bases which are commonly found
in the laboratory are sodium hydroxide, potassium hydroxide, and ammonium hydroxide.