acidity would clearly be quite useful. A
simple scale has been devised to provide just
that.
The pH Scale The standard measure of proton
activity in solutions is pH, a term suggested
by the Danish chemist S. P. L. Sørenson in
- It’s essentially a more convenient
version of the minuscule percentages of
molecules involved (for some details, see box
below). The pH scale runs from 0 to 14. The
pH of neutral, pure water, with equal numbers
of protons and OH ions, is set at 7. A pH
lower than 7 indicates a greater concentration
of protons and so an acidic solution, while a
pH above 7 indicates a greater prevalence of
proton-accepting groups, and so a basic
solution. Here’s a list of common solutions
and their usual pH.
Liquid pH
Human gastric juice 1.3–3.0