PH

The term pH is derived from the French Puissance d'hydrogène ("power of hydrogen"), which refers to the power of 10 (the exponent) used to express the molar H₃O⁺ (hydronium ion) concentration. The pH scale has values that range from 0 (very acidic) to 14 (very basic), that relates the hydronium ion concentration to a number. This serves as a useful indicator of the degree of acidity or basicity of the solution, where pH 7, the middle of the scale is neutral (neither acidic nor basic).