What defines an acidic solution in chemical terms?

An acidic solution is characterized by an excess of hydrogen ions (H+). In chemical terms, when a solution has a higher concentration of H+ ions compared to hydroxide ions (OH-), it is classified as acidic. This is fundamental to the Brønsted-Lowry definition of acids and bases, where acids are defined as proton donors. In a typical acidic solution, the pH value is less than 7, indicating this excess of hydrogen ions.

The other options do not accurately describe an acidic solution. The presence of an excess of OH- ions defines a basic or alkaline solution, while the dissociation of alkali refers to the process by which alkalis release hydroxide ions into the solution. The last option pertains to electrochemistry, which is unrelated to the definition of acidity in chemical solutions. Thus, the defining characteristic of an acidic solution is indeed an excess of H+ ions.