Table of Contents

pH Scale

In chemistry, pH, historically denoting “potential of hydrogen” (or “power of hydrogen”), is a scale used to specify the acidity or basicity of an aqueous solution.
Acidic solutions (solutions with higher concentrations of H+ ions) are measured to have lower pH values than basic or alkaline solutions.
At 25 °C (77°F), solutions with a pH less than 7 are acidic, and solutions with a pH greater than 7 are basic
The concept of pH was first introduced by the Danish chemist Soren Peder Lauritz Sorensen at the Carlsberg Laboratory in 1909.
The first electronic method for measuring pH was invented by Arnold Orville Beckman.
pH is a measure of how acidic / basic water is.
The range goes from 0 – 14, with 7 being neutral.
pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base.
pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.
Water that has more free hydrogen ions is acidic, whereas water that has more free hydroxyl ions is basic.

The pH scale is used to rank solutions in terms of acidity or basicity (alkalinity).
Since the scale is based on pH values, it is logarithmic, meaning that a change of 1 pH unit corresponds to a ten-fold change in H+ ion concentration.
The pH scale is often said to range from 0 to 14, and most solutions do fall within this range, although it’s possible to get a pH below 0 or above
Anything below 0 is acidic, and anything above 7.0 is alkaline, or basic.

pH value of some substances