Freshman chemistry students' microscopic interpretations of their visible observations of melting and dissolving

CHED 4

K. Chris Smith, smith438@purdue.edu and Mary B. Nakhleh, mnakhleh@purdue.edu. Department of Chemistry, Purdue University, 560 Oval Drive, West lafayette, IN 47907
Our study investigated how university freshman chemistry students interpreted the molecular behavior of common compounds in relation to observations of their macroscopic properties. We conducted semi-structured interviews with 23 students during which the students made predictions and experimental observations on the melting of four compounds: sugar, salt, butter, and chalk. The students also made predictions and experimental observations on the interactions of these four compounds with water and cooking oil. Students provided microscopic-level explanations and drawings to support their observations. Our analysis indicated that students tended not to consider particle motion in systems undisturbed by external factors, such as salt settled in a beaker of water. Students did tend to consider particle motion in systems affected by external factors, such as heating and stirring. Students exhibited a range of ideas on bonds and/or the intermolecular forces affected by melting and dissolving. We will discuss our analysis and implications for teaching.
 

Research in Chemical Education
8:30 AM-11:35 AM, Sunday, March 25, 2007 McCormick Place North -- Room N227A, Level 2, Oral

Division of Chemical Education

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007