|What is pH|
pH is a measure of the hydorgen ion concentration of a solution. Solutions with a high concentration of hydrogen ions have a low pH and solutions with a low concentrations of H+ ions have a high pH. This may seem like a confusion way to express these reationships, and it is, until you understand what pH stands for. The equation that defines pH is given as follows:
which is read:
the pH is equal to minus the log of the H+ concentration.
For example is the H+ concentration is very low, lets say about 0.0000001M, then the pH is
pH= -log[.0000001] whis is the same as -log[1 X 10-7]
the term log[1 X 10-7] = -7
- (-7) = 7
Look at the following table
|hydrogen ion concetration||pH||solutions with a pH of|
|.01M||2||coke and orange juice|
From this table you will notice a few relationships
a difference of one pH unit (ie from pH 2 to pH 3) is a ten fold (10X) difference in H+ ion concentration.
pure water should have a pH of 7.0
solutions with a pH below 7.0 are termed acidic and solutions with a pH above 7.0 are termed basic.