pH stands for the
power of hydrogen. pH is defined as a unit or measure to show the
concentration of hydrogen ion (H+). When the pH is 7, the solution is
neutral. In other words the concentration of H+ is equal to the
concentration of OH-.
Solutions with pH
lower than 7 are acidic. Solutions with pH higher than 7 are alkaline.
The pH in strong
acids is 0. The pH in strong alkalis is 14.
To be more
The pH is the negative logarithm of the
hydrogen ion concentration. A complete definition requires that the
logarithm is defined as being to the base ten and the concentration be
measured as activity in moles per liter. Confusion arises because, as
the acidity increases, the pH decreases. To avoid mistakes when
discussing acid-base balance, it is often safer to avoid
"increase" and "decrease" and use "more
acid" and "more alkaline" instead.
|pH - what it means.
Log (Base 10) of [H+] in Mol/L
To understand logarithm, think of
"power." Thus 103 = 1000 and log (1000) = 3. When
the pH changes by 0.3 units, e.g., from 7.4 to 7.1 the hydrogen ion
concentration doubles (from 40 to 80 nMol/1). Wouldn't [H+]
be so much easier to understand?
Logarithm is another source of confusion
in acid base balance and is responsible for the mistaken impression that
the body maintains remarkably tight control over its hydrogen ion
concentration - it doesn't. (Blood pressure or pulse measured with a
logarithmic notation would appear equally stable). To remember how to
understand logarithm, think of "power." Thus 103 =
1000 and log (1000) = 3. When the pH changes by 0.3 units, e.g., from
7.4 to 7.1 the hydrogen ion concentration doubles (from 40 to 80 nMol/1).
Wouldn't [H+] be so much easier to understand?
(1000) = 3
This program will calculate the pH of a solution of known