Understanding Chemical and Physical Phenomena
Understanding chemistry is challenging for many students because they need to conceptualize and relate chemical phenomena at three levels: macroscopic, symbolic, and submicroscopic levels (Johnstone, 1993; Taber, 2013). Students cannot easily make connections between observable changes and submicroscopic explanations (Lekhavat & Jones, 2009) and they may have misconceptions about chemical or physical processes.
Even though students observe many physical phenomena, such as evaporation and condensation, in their everyday lives, they may not have a good understanding of what is really happening at a submicroscopic level. Recent studies have shown that tertiary students have a tendency not to refer to the submicroscopic level when describing the processes of evaporation and condensation (Gobal et. al., 2004). They also exhibit a weaker understanding of condensation than of evaporation, and tend to believe that the level of an open container of water would remain constant during evaporation. Many precollege students think that during evaporation, water separates into hydrogen and oxygen atoms (Osborne & Cosgrove, 1982). Azizoglu, Alkan, and Geban (2006) reported that pre-service teachers held many misconceptions about physical changes, for example, many of them believed that the vapor pressure of a liquid depends on the volume of its container and that the freezing point is independent of pressure. Canpolat, Pinarbasi, and Sozbilir (2006) found additional misconceptions in their study of pre-service teachers, namely that they tended to believe vaporization does not begin until a liquid boils and that different liquids boiling at atmospheric pressure have different vapor pressures at their boiling points.