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- All Subjects: Chemistry, Organic
- Creators: Gould, Ian R.
Description
Guided by cognitive, socio-cognitive, and socio-cultural learning theories, large-scale studies over multiple semesters, multiple instructors and at two different institutions have been performed in order to understand the factors that contribute to student performance in general organic chemistry. Students’ cognitive abilities were assessed in a new way based on a categorization of problem types in a standard organic chemistry curriculum. Problem types that required higher cognitive load were found to be more predictive of overall course performance. However, student performance on high cognitive load problems was different when compared in terms of non-cognitive factors, e.g. whether they were pre-health students or not. These results suggested that organic chemistry performance may be significantly influenced by non-cognitive factors. Students’ motivation and related self-regulation factors were then studied using an instrument specifically designed for general organic chemistry, the Organic Chemistry Motivation Survey. Of all the factors examined, self-efficacy was found to be the most significant predictor of performance. Socio-cultural factors were also studied using a newly developed instrument for measuring college students’ cultural and social capital, the Science Capital Questionnaire (SCQ). Of the different socio-cultural variables measured by the SCQ, students’ social connections in college were found to be most predictive of organic chemistry performance. Finally, cognitive and socio-cognitive variables were studied together in the context of gender differences in organic chemistry. Females were found to underperform in comparison to the males. This gap was found to be alarmingly large on the basis of final letter grade, in some semesters the percentage of males earning an A grade was twice as large as that for females. Spatial ability was not a factor that contributed to this difference, nor was the gender of the instructor. Instead, self-efficacy was found to be both significantly different between males and females, and also the factor that connected most strongly to course performance. It is suggested that sociocultural factors be the subject of further study in college science courses.
ContributorsAustin, Ara Cho (Author) / Gould, Ian R. (Thesis advisor) / Atkinson, Robert K. (Committee member) / Williams, Peter (Committee member) / Arizona State University (Publisher)
Created2018
Description
Hydrothermal systems are not the typical environments in which organic chemistry is studied. However the organic reactions happening there are increasingly implicated in non-trivial geochemical processes. For example, the origins of life, the formation and degradation of petroleum, and feeding the deep biosphere. These are environments where water is heated and pressurized until it has a polarity more typical of an organic solvent and an increased dissociation constant that decreases its pH. In addition, these environments host many transition metal oxide and sulfide minerals that are not inert bystanders to the chemistry happening around them. This thesis takes from the environment the complicated matrix of hot pressurized water, organic material, and minerals, and breaks it down, systematically, in the laboratory to probe the effects hydrothermal conditions and minerals have on the reactivity of model organic compounds. I conducted experiments at 300°C and 100 MPa using water, organic reactants, and minerals. Methyl- and dimethyl-cyclohexane based reactants provided regio and sterio-chemical markers to indicate reaction mechanisms. Without minerals, I found that the cyclic alkanes undergo a series of reversible stepwise oxidation and hydration reactions forming alkenes-alcohols-ketones, and alkenes-dienes-aromatic rings. I also found the reactions to be reversible; the ketone was readily reduced to the alkane. When the reactions were carried out in the presence of minerals, there were sometimes dramatic effects including reaction rate enhancement and changes in product distributions. Minerals pushed the reaction in the direction of oxidation or reduction depending on the type of mineral used. The hydration reaction could be essentially “turned off” using pyrite (FeS2) and troilite (FeS), which eliminated formation of ketone products. In contrast, hematite (Fe2O3) and magnetite (Fe3O4) favored the hydration reaction and enhanced ketone production. Sphalerite (ZnS) was shown to act as a heterogeneous catalysis for alkane isomerization by activating the C-H bond and increasing reaction rates until thermodynamic equilibrium was reached. This suggests that the types of minerals present in hydrothermal environments will affect the functional group composition of organic material. Minerals and hot pressurized water may also have useful applications in organic chemistry as “green” reactants and catalysts.
ContributorsShipp, Jessie (Author) / Hartnett, Hilairy H. (Thesis advisor) / Gould, Ian R. (Committee member) / Shock, Everett L. (Committee member) / Arizona State University (Publisher)
Created2013