Diagrammatic representation of the dissociation of acetic acid in aqueous pho to acetate and hydronium ions. H values than basic or alkaline solutions.

The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution. H less than 7 are acidic, and solutions with a pH greater than 7 are basic. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Briggsian logarithm of the related hydrogen ion normality factor is to be understood. The exact meaning of the letter p in “pH” is disputed, as Sørensen did not explain why he used it.