This study aimed to investigate the impacts of contextual factors on the use of students' conceptions. A total of 106 students received a questionnaire involving open-ended questions on acid-base and equilibrium concepts. Of these students, 16 students who provided complete and accurate responses to the questions participated in an interview. In order to observe the effects of different contexts, in the interview, the conception of acid-base was probed in an equilibrium system. As a result, the students' utterances indicated that (1) a specific problem situation could activate a different part(s) of a concept image, (2) an evoked concept image perfectly working in a particular context could become inadequate in a broader one, and (3) a misconception that could not be observed in a particular context might surface itself in a different one. The results further pointed to the fact that our current definitions and descriptions for acids and bases could be one of the sources of these misconceptions.