The term
pH comes from Latin. It meas "pondus hydrogenii"
hydrogen weight. Another possible
meaning is potentia hydrogenii
= hydrogen effectivity.
The
value of pH is very important
regarding industry, medicine,
food sector and agriculture.
Although the pH is mostly measured
in aqueous solutions it can be also
defined in solids (fruits) and in
the human body (the value of
pH in the human skin). In order to
get appropriate results, it is
important to perform the measurement
in an object with a proper moisture
content. The pH is determined by
means of pH indicators or with
digital measuring instruments
pH indicators are substances that
change color around a particular pH
value.
With both testing strings and paper indicators
less precise results have been
discovered. With
the digital pH meters you can get a
quick and proper results.
pH is defined as minus the decimal
logarithm
of the
hydrogen ion
activity in an aqueous solution.[7]
By virtue of its logarithmic nature,
pH is a
dimensionless
quantity.
pH = - lgaH+
Solutions with a pH
less than 7 are said to be
acidic
and solutions with a pH greater than
7 are said to be
basic
or
alkaline.