1909 – Denmark
‘A scale of acidity and alkalinity. It runs from 0 (most acid) to 14 (most alkaline).
A neutral solution has a pH of 7’
A solution is acidic when the pH is less than 7 and basic (alkaline) when the pH is greater than 7.
The scale is logarithmic.
The pH measures the concentration of hydrogen ions, H+ , in water.
pH is defined as the negative logarithm of the hydrogen ion concentration.
The pH scale can only be used for solutions of acids and bases in water.