Relating macroscopic observations of melting and *mixing to microscopic explanations

Kenneth Christopher Smith, Purdue University

Abstract

This study investigated how freshman and graduate chemistry students interpreted the particle behavior of common compounds in relation to observations of their macroscopic properties. Semi-structured interviews were conducted with 30 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 particulate-level explanations and drawings to support their observations. Analysis indicated that students tended not to consider particle motion in systems undisturbed by external factors, such as when salt settles in a beaker of water. However, students did tend to consider particle motion in systems affected by external factors, such as heating and stirring. Students exhibited six bonding misconceptions, but discussed other particulate-level features, such as particle order and spacing, readily. Misinterpretation of observations sometimes led to faulty conclusions by the students, and graduate students gave some explanations which highlighted their chemistry experience, compared to the undergraduates.

Degree

Ph.D.

Advisors

Nakhleh, Purdue University.

Subject Area

Chemistry|Science education

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