A discussion of some student conceptions
of the solid–liquid
and liquid–vapor phase transitions is presented. Data from
open-ended, short-answer questions were collected from first-semester
general chemistry students and then discussed in the context of previous
studies. The responses gave insight into the various student conceptions
about these phase changes. Student misunderstandings were most often
related to (i) contextual difficulties with the terms freezing and boiling associated with their lack of experience
with different substances, (ii) misinterpretation of physical and
chemical phenomena, either from everyday experience or classroom demonstrations,
and (iii) the inability to understand energy transfer processes. Specific
implications for the teaching of topics related to freezing and boiling are also addressed.