Student performance in two first-semester general chemistry courses are compared to determine whether a distance learning model can provide a comparable learning opportunity to the conventional lecture–laboratory format. The conventional course was taught at a midsized, southeastern university; the distance learning course was taught through a community college. The laboratory portion of the distance learning course consisted of at-home (kitchen chemistry) experiments. For the first two semesters (Version I), the lecture portion of the course was delivered via the Internet and the students met on campus each week for a laboratory–recitation session. For the following three semesters (Version II), all instruction was offered via the Internet. In every semester, distance learning students achieved higher average scores than their university counterparts on common final exams. In laboratory practicals, distance learners demonstrated manipulation, data analysis, and data reporting skills that surpassed those of the students in the conventional course. These results suggest that this distance learning model for teaching chemistry can be an effective alternative to conventional teaching methods for the types of students who typically succeed in a distance learning environment. The results also demonstrate a unique approach to helping students appreciate the relevance of chemistry to their daily lives.
Many of us use commercially available sunscreens to protect us from sunburn, premature aging, and skin cancer, but what is the chemistry behind their function? This article describes how light energy interacts with molecules to produce excited states, the behavior of those excited states, the particular pathways that result in ultraviolet protection, and the relationship between concentration and absorption. Structures of substances used in sunscreen preparations and their accompanying regions of UV-absorption are provided. A brief discussion of the "Sun Protection Factor" or SPF that appears on the labels of sunscreen preparations is also included.
Four exciting chromatography activities. Simple and effective method of column chromatography of leaf pigments using chemicals and equipment that can be purchased at most grocery, hardware, and/or drugstores.
Making a laboratory science course accessible to distance learners requires eliminating certain barriers. This paper describes one semester introductory chemistry courses for science and non-science majors that feature laboratory experiments that students can do at home, using materials readily available from local grocery and hardware stores. Courses using this approach have been offered successfully for several years at the University of Colorado at Denver, Cape Fear Community College and the University of North Carolina at Wilmington, and the laboratory experiences of the distance learners compares favorably with that of traditional students. This paper describes the important features of the distance learning courses, and provides assessment results that indicate the suitability of these experiments as replacement for traditional laboratories.
The action of the enzyme catalase on aqueous hydrogen peroxide to generate oxygen gas is a well-established demonstration. Catalase is typically obtained by aqueous extraction of a potato, and the potato extract is mixed together with 3% hydrogen peroxide. The oxygen that is produced can be collected over water. Variations on the procedure can demonstrate the dependence of catalytic activity on temperature or the presence of inhibitors.
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