DISSERTATION I. COGNITIVE AND INSTRUCTIONAL FACTORS RELATING TO STUDENTS’ DEVELOPMENT OF PERSONAL MODELS OF CHEMICAL SYSTEMS IN THE GENERAL CHEMISTRY LABORATORY II. SOLVATION IN SUPERCRITICAL CARBON DIOXIDE/ETHANOL MIXTURES STUDIED BY MOLECULAR DYNAMICS SIMULATION Submitted by Seth Anthony Department of Chemistry In partial fulfillment of the requirements For the Degree of Doctor of Philosophy Colorado State University Fort Collins, Colorado Spring 2014 Doctoral Committee: Advisor: Dawn Rickey Co-Advisor: Branka M. Ladanyi Grzegorz Szamel Amy L. Prieto Edward L. DeLosh Copyright by Seth Anthony 2014 All Rights Reserved ABSTRACT I. COGNITIVE AND INSTRUCTIONAL FACTORS RELATING TO STUDENTS’ DEVELOPMENT OF PERSONAL MODELS OF CHEMICAL SYSTEMS IN THE GENERAL CHEMISTRY LABORATORY II. SOLVATION IN SUPERCRITICAL CARBON DIOXIDE/ETHANOL MIXTURES STUDIED BY MOLECULAR DYNAMICS SIMULATION Part I. Students’ participation in inquiry-based chemistry laboratory curricula, and, in particular, engagement with key thinking processes in conjunction with these experiences, is linked with success at the difficult task of “transfer” – applying their knowledge in new contexts to solve unfamiliar types of problems. We investigate factors related to classroom experiences, student metacognition, and instructor feedback that may affect students’ engagement in key aspects of the Model-Observe-Reflect-Explain (MORE) laboratory curriculum – production of written molecular-level models of chemical systems, describing changes to those models, and supporting those changes with reference to experimental evidence – and related behaviors. Participation in introductory activities that emphasize reviewing and critiquing of sample models and peers’ models are associated with improvement in several of these key aspects. When students’ self-assessments of the quality of aspects of their models are solicited, students are generally overconfident in the quality of their models, but these self-ratings are also sensitive to the strictness of grades assigned by their instructor. Furthermore, students who produce higher-quality models are also more accurate in their self-assessments, suggesting the importance of self-evaluation as part of the model-writing process. While ii the written feedback delivered by instructors did not have significant impacts on student model quality or self-assessments, students’ resubmissions of models were significantly improved when students received “reflective” feedback prompting them to self-evaluate the quality of their models. Analysis of several case studies indicates that the content and extent of molecular-level ideas expressed in students’ models are linked with the depth of discussion and content of discussion that occurred during the laboratory period, with ideas developed or personally committed to by students during the laboratory period being likely to appear in students’ post-laboratory refined models. These discussions during the laboratory period are primarily prompted by factors external to the students or their laboratory groups such as questions posed by the instructor or laboratory materials. Part II. Solvation of polar molecules within non-polar supercritical carbon dioxide is often facilitated by the introduction of polar cosolvents as entrainers, which are believed to preferentially surround solute molecules. Molecular dynamics simulations of supercritical carbon dioxide/ethanol mixtures reveal that ethanol molecules form hydrogen-bonded aggregates of varying sizes and structures, with cyclic tetramers and pentamers being unusually prevalent. The dynamics of ethanol molecules within these mixtures at a range of thermodynamic conditions can largely be explained by differences in size and structure in these aggregates. Simulations that include solute molecules reveal enhancement of the polar cosolvent around hydrogen-bonding sites on the solute molecules, corroborating and helping to explain previously reported experimental trends in solute mobility. iii ACKNOWLEDGEMENTS I began my journey towards a Ph.D. emphasizing chemistry education in order to learn what made science instruction truly effective, to contribute in a small way to that body of knowledge, and, most importantly, to learn how to become the most effective chemistry teacher that I could be. When I look back on the journey that has led me here, I’m reminded of the many individuals who have encouraged, supported, challenged, and guided me down this path, and I wish to acknowledge just a few of the most important here. My journey towards being a scientist and a teacher was sparked in so many ways by my grandmother, Betty Dilday, who bought me my very first chemistry set when I was in the second grade and who listened – patiently and with genuine interest – to many of my early attempts at teaching – explaining the internet, sailboats, or black holes. Her encouragement of my curiosity and natural interest in explaining the world – to myself or to others – has truly set me off on my path in life. I would not be where I am today without having been pushed by amazing teachers during my entire academic career. When I think about my love of science and mathematics, I cannot help but think back all the way to elementary school and the classrooms of Ms. Carol Nebrat and Ms. Phyllis Beeson, who not only encouraged my enthusiasm, but encouraged me to share my discoveries and joy in science and math with others. In college at North Carolina State University, I was mentored and encouraged by a number of professors who pushed me in the direction that I finally took. This included Dr. Kay Sandberg, who first got me involved in undergraduate research; Dr. Brent Gunnoe, in whose lab I learned that I am in no sense a synthetic iv chemist; Dr. Jonathan Kramer, who encouraged me to think outside the box in pursuing my academic interests; and Dr. Maria Oliver-Hoyo, without whom I wouldn’t have even known chemistry education existed as a field of study. I would be remiss if I neglected to mention the late Dr. J.R. Boyd, who taught at the Governors’ School of North Carolina, and who demonstrated by example how non-traditional teaching methods could engage talented students. Foremost among the teachers who have inspired me, though, is Dr. Forrest Hentz, in whose general chemistry class I saw firsthand the joys of learning and teaching chemistry, and who remains my role model for inspiring and engaging students whenever I step into a classroom. Once I reached Colorado State University for graduate work, my chemistry education research wouldn’t have been possible without the support of Colorado State University’s chemistry department for innovations within the curriculum – for this, I want to thank the department chairs during my time here, Dr. Tony Rappe and Dr. Ellen Fisher. I also wish to thank Dr. Nancy Boldt, the general chemistry laboratory coordinator, and all of the staff on the 4th floor of Yates Hall, for understanding as I barged into and out of dozens of chemistry lab classrooms with video cameras and stacks of lab reports to scan. My graduate advisors– Dr. Dawn Rickey and Dr. Branka Ladanyi – have been amazingly supportive, demanding high-quality work from me while expressing confidence which I did not always have in my ability to complete it. I especially want to thank them for their patience and understanding as I sought to juggle two essentially unrelated projects – one in chemistry education, one in physical chemistry – as part of my graduate program, and as completing my graduate program took longer than I anticipated when started a faculty job while not yet done writing this dissertation. I v must also acknowledge Dr. Ken Usher, my department chair in my new job at Oregon Institute of Technology, for his understanding and gentle encouragement towards finishing this dissertation. I am also grateful to faculty both within Colorado State University’s chemistry department and outside it who have encouraged and supported me in my graduate career and offered helpful advice, particularly Dr. Amy Prieto, Dr. Nancy Levinger, Dr. Matt Rhodes, Dr. Lisa Dysleski, Dr. Melonie Teichert, and Dr. Lydia Tien. Without their guidance, mentorship, and encouraging conversations, my graduate program would have looked much different. To my colleagues and office-mates in the chemistry department – particularly Laura Wally, Colin Blair, and Ryan Trott in the chemistry education group, and Dr. Janamajeya Chowdhary and Dr. Anatoli Milischuk in the physical chemistry group, I offer sincere thanks for sharing laughter, frustration, and meaningful conversations about research and the process of research. My family has always shown tremendous confidence in me, and I can only hope that I can continue to live up to their expectations. The lessons I’ve learned from them are too numerous to list,but I must acknowledge my father, who taught me to always check my assumptions, and my mother, who taught me to always persist through difficult situations. Most importantly, I am unendingly grateful to my wife, Eve Klopf, who has shared this journey towards a Ph.D. alongside me. Life is so much richer when you have someone to share both joys and frustrations with, and I do not believe I would have been able to reach this finish line without her support, encouragement, and unfailing confidence Thank you, all, for your support on this journey. vi DEDICATION This dissertation is dedicated to my grandmother, Betty Dilday, who began me on my journey to learn, to teach, and to try to make the world a better place