eng Science and Education Publishing World Journal of Chemical Education 2013-11-22 1 1 12 16 10.12691/wjce-1-1-4 WJCE2013114 article Toratane Munegumi tmunegumi@naruto-u.ac.jp 1 Department of Science Education, Naruto University of Education, Naruto, Tokushima, Japan The strength of an acid is generally discussed as a unique feature of the acid itself according to its chemical structure. Strong acids have a lower pKa value, and weak acids have a higher one. In the classrooms of high schools and universities, we sometimes use the technical terms “strong acid” and “weak acid”. However, there are some acids for which it is very difficult to say, from their pKa values, whether they are strong or weak. This research addresses the distinction between strong acids and weak acids, in a restricted initial concentration of acids, to provide a clear distinction between strong acids and weak acids. http://pubs.sciepub.com/wjce/1/1/4/wjce-1-1-4.pdf strong acidweak acidpKadegree of dissociation