An operational definition is one based on experimental observations and includes a set of conditions to apply when a term is used in a particular situation. A conceptual definition is based on the interpretation of observed facts. Go to top . A. Acids Understandings and Fundamental Concepts Acids may be defined in terms of their characteristic properties. Acids will react with certain metals to liberate hydrogen gas.
Acids cause color changes in acid-base indicators.
Acids react with hydroxides to form water and a salt. Dilute aqueous solutions of acids have a sour taste. These properties can be observed experimentally, and form the basis of the operational definition of an acid. Acids conduct electricity in relation to the degree of their ionization. Acids will react with those metals below hydrogen in the Table of Standard Electrode Potentials given in Reference Tables for Chemistry.