Freshman Chemistry Course Research Articles

Demonstrations of Frequency/Energy Relationships Using LEDs

The use of LEDs (light-emitting diodes) to demonstrate the relationship between frequency (or wavelength) and semiconductor energy level differences is described. LEDs can function as light detectors, and this ability is exploited to show the minimum light frequency needed to produce a voltage response in the LED. Light having higher energy (lower wavelength) than the detector LED bandgap energy produces a significant voltage response, whereas lower-energy light results in minimal response. The light sources can be other LEDs or a flashlight with colored filters. Alternatively, the voltage measured across an LED as it emits light under power can also be related to the LED bandgap energy, providing a somewhat more accurate estimate of the bandgap energy than that obtained from the LED detector mode. Although these demonstrations using LEDs are not technically the same as the classic photoelectric effect as presented in most freshman chemistry courses, they nevertheless illustrate the same relationships bet...

Web-based undergraduate chemistry problem-solving: The interplay of task performance, domain knowledge and web-searching strategies

This study investigates the effect of Web-based Chemistry Problem-Solving, with the attributes of Web-searching and problem-solving scaffolds, on undergraduate students' problem-solving task performance. In addition, the nature and extent of Web-searching strategies students used and its correlation with task performance and domain knowledge also were examined. We recruited a total of 183 undergraduate students, all of whom are taking the freshman chemistry course, to participate in the study to solve three chemistry tasks across a semester. Mandated screen-capture software captured participants' on-screen Web-searching processes were recorded every five seconds. Results demonstrated that students' problem-solving performance was significantly improved from task 1 to 3, and students with more domain knowledge outperformed students with less domain knowledge. Students with higher problem-solving performance employed more existing knowledge and metacognitive Web-searching strategies; and students with lower problem-solving performance employed more cognitive Web-searching strategies. In addition, students' problem-solving performance was correlated with their domain knowledge, use of existing knowledge, and metacognitive Web-searching strategies. Moreover, students' use of existing knowledge was the major factor for predicting their problem-solving performance according to the regression model.

Enzyme Kinetics and the Michaelis-Menten Equation

The concepts presented in this article represent the cornerstone of classical mathematical biology. The central problem of the article relates to enzyme kinetics, which is a biochemical system. However, the theoretical underpinnings that lead to the formation of systems of time-dependent ordinary differential equations have been applied widely to any biological system that involves modeling of populations. In this project, students first learn about the general balance equation, which is a statement of conservation within a system. They then learn how to simplify the balance equation for several specific cases involving chemically reacting systems. Derivations are reinforced with a concrete experiment in which enzyme kinetics are illustrated with pennies. While a working knowledge of differential equations and numerical techniques is helpful as a prerequisite for this set of activities, all of the requisite mathematical skills are introduced in the project, so the methods would also serve as an introduction to these techniques. It is also helpful if students have some basic understanding of chemical concepts such as concentration and reaction rate, as typically covered in high school or college freshman chemistry courses. [Supplementary materials are available for this article. Go to the publisher's online edition of PRIMUS for the following free supplemental resource(s): Appendices and Sample Solution]

Bringing the Excitement of Biological Research into the Chemistry Classroom at MIT

A ll Massachusetts Institute of Technology (MIT) undergraduates are required to take introductory chemistry, which means that their willing or unwilling ears are ours for a full semester. MIT therefore has the unique opportunity to instill an appreciation of chemical principles in every incoming student, including those who left high school with an ambivalent or negative view of chemistry. Two classes within the chemistry department fulfill MIT’s basic chemistry requirement, with the more advanced course attracting the majority of those students already excited about chemistry. Here, we discuss our plans for the other course, Principles of Chemical Science 5.111, which is composed of students who are generally not planning on chemistry or engineering majors, 25% of each freshman class. Among this group, there is considerable interest in biology. Many students express a passion for cancer research and the biology of disease but claim they “hate chemistry”. Few understand that chemical reactions are at the heart of biological processes, from the workings of a cell to the inhibition of cancer targets. By demonstrating the relationship between chemistry and biology, we hope to harness the students’ enthusiasm for biology and medicine to increase their interest in andunderstanding of chemistry. This enriched introductory chemistry course is central to a larger initiative, funded by the Howard Hughes Medical Institute (HHMI) Professors Program, aimed at increasing the understanding of chemical principles among biology students and demonstrating the vital connection between biology and chemistry. Similar to the overall program goals, our hope for the course is to foster an understanding of chemistry’s relevance by illuminating the centrality of chemistry in biological and medicinal research. Although scattered biological examples have been part of our curriculum for several years, this fall will mark the first full run of the more biologically focused course. In this article, we outline the changes that have been implemented and the feedback we have thus far received. With an assessment plan in place, we look forward to reporting successes and pitfalls as the program continues. Course Material. In compiling biologically enriched material for the freshman chemistry course, our intent is not to create a combined chemistry and biology course or even to change the current curriculum, which has been set by the MIT chemistry department. Instead, our approach is to invigorate the lectures and associated problem sets with biological examples that illustrate each concept presented. We hope that the placement of relevant examples and research applications of a given chemical principle will give new context to the course material. This approach has already been implemented on a smaller scale by presenting several biological examples per semester that bring the excitement of research into the classroom. For example, in teaching about the 3D *Corresponding author, evogel@mit.edu.

A Procedural Problem in Laboratory Teaching: Experiment and Explain, or Vice-Versa?

This work describes two different approaches to teaching the laboratory segment of a freshman chemistry course. In Approach I, each experiment was explained and demonstrated to the students before ...

Using a Socratic Dialog To Help Students Construct Fundamental Concepts

The concept of gravitational mass is usually introduced to chemistry students as a measure of the amount of matter in a given object. Although this definition can be useful as a starting point for quantitative investigations in chemistry, it does not refer explicitly to the direct experimental observations upon which the concept is actually based. This traditional approach also misses an opportunity to help students connect observations in the see-touch world with inferences about the atomic realm, and may contribute to the incomplete understanding exhibited by many high school and first-year college students of mass and other fundamental concepts, like weight and density. This paper presents a Socratic dialog between a hypothetical instructor and student, which uses experimental evidence and operational definitions to introduce these concepts. The student's responses are based on those of many individuals in a college freshman chemistry course, and point out the difficulties associated with learning the concepts. The question sequence has evolved to its current form based on student feedback obtained over the course of several years. A theoretical basis for this type of instruction is discussed, as well as the benefits and challenges associated with its application to this particular material.

Cigarette Smoke Analysis Using an Inexpensive Gas-Phase IR Cell

An inexpensive, break-resistant IR gas cell has been constructed using a PVC compression tee. The cell allows for multiple experiments to be performed in freshman chemistry and advanced lab courses. The PVC cell can be assembled by the students and then dismantled and cleaned after their experiments are completed. This cell has been successfully used to analyze some of the components of cigarette smoke and car exhaust.

Tablet Analysis Using Gravimetric Dilutions

This experiment introduces the concept of gravimetric dilutions in the context of tablet analysis. Caffeine tablets are analyzed by absorbance at 274 nm with reference to a standard calibration graph and tested for compliance with the USP criterion. All samples and standards are prepared using gravimetric dilutions without reference to volume or density. This experiment is appropriate for high school and college freshman chemistry courses and may be useful at higher levels. It is only necessary that students have had exposure to Beer's law.

Piltdown Man: Combining the Instruction of Scientific Ethics and Qualitative Analysis

In combination with lectures on scientific method and the problems of scientific misconduct in a freshman chemistry course at The University of Alabama, a laboratory experiment was developed to allow students to feel some of the sense of scientific discovery associated with the exposure of the Piltdown Man fraud. This is accomplished by modifying a commonly performed freshman chemistry laboratory experiment, qualitative analysis of group III metal ions. Pieces of chalk are treated with chromium, manganese, and iron to simulate the treatment used to forge the Piltdown fossils; students can use techniques in qualitative analysis schemes for the group III ions to determine whether the samples are forgeries and if so which metal ion(s) were used.

An Experimental Curriculum for Introductory Chemistry: "Research! A Freshman Experience in the Excitement of Chemistry"

Describes two freshman chemistry courses (one studying batteries and the other the preservation of genomes) which focus on original research as a means of motivating students and promoting careers in the natural sciences.

Relationships Between Achievement and Selective Variables in a Chemistry Course for Nonmajors

The main purpose of this study was to investigate the relationships between students' approaches to studying, prior knowledge, logical thinking ability, and gender and their performance in a nonmajors' college freshman chemistry course. Subjects for this study were 220 students (128 females and 92 males) enrolled in the second semester of a freshman chemistry course for nonmajors at a private university in New York State. Instruments used in this study included seven subscales of the Approaches to Studying Inventory and the Test of Logical Thinking (TOLT). The students' grades on an hour‐long exam early in the semester were used as measures of the students' prior knowledge, while the semester cumulative final examination scores were used as measures of achievement in chemistry. Students in this study had slightly higher scores on reproducing orientation than on meaning orientation, a pattern that confirms Entwistle and Ramsden's (1983) findings with a similar group of nonmajors. The results of a stepwise multiple regression showed that prior knowledge, TOLT scores, and meaning orientation accounted for 32% of the variance on the final examination scores.

Highlights: Ventures in freshman chemistry

A rigorous freshman chemistry course that prepares students for further study in chemistry and natural sciences ties principles of chemistry to energy and environment.

Required writing in freshman chemistry courses

Thoughtful writing assignments make laboratory experiences more meaningful for introductory students.

Enhancing chemistry problem‐solving achievement using problem categorization

AbstractThe enhancement of chemistry students' skill in problem solving through problem categorization is the focus of this study. Twenty‐four students in a freshman chemistry course for health professionals are taught how to solve problems using the explicit method of problem solving (EMPS) (Bunce & Heikkinen, 1986). The EMPS is an organized approach to problem analysis which includes encoding the information given in a problem (Given, Asked For), relating this to what is already in long‐term memory (Recall), and planning a solution (Overall Plan) before a mathematical solution is attempted. In addition to the EMPS training, treatment students receive three 40‐minute sessions following achievement tests in which they are taught how to categorize problems. Control students use this time to review the EMPS solutions of test questions. Although problem categorization is involved in one section of the EMPS (Recall), treatment students who received specific training in problem categorization demonstrate significantly higher achievement on combination problems (those problems requiring the use of more than one chemical topic for their solution) at (p = 0.01) than their counterparts. Significantly higher achievement for treatment students is also measured on an unannounced test (p = 0.02). Analysis of interview transcripts of both treatment and control students illustrates a “Rolodex approach” to problem solving employed by all students in this study. The Rolodex approach involves organizing equations used to solve problems on mental index cards and flipping through them, matching units given when a new problem is to be solved. A second phenomenon observed during student interviews is the absence of a link in the conceptual understanding of the chemical concepts involved in a problem and the problem‐solving skills employed to correctly solve problems. This study shows that explicit training in categorization skills and the EMPS can lead to higher achievement in complex problem‐solving situations (combination problems and unannounced test). However, such achievement may be limited by the lack of linkages between students' conceptual understanding and improved problem‐solving skill.

Using a macintosh-based molecular graphics package in freshman and upper-level chemistry courses

Using a macintosh-based molecular graphics package in freshman and upper-level chemistry courses

Potentiometric titration of acidic and basic compounds in household cleaners

The potentiometric titration of commercial household cleaners can be used in student laboratories in freshman, analytical, and physical chemistry courses. It can be used for analysis of household cleaners with either one or two component systems, or it can be used for the determination of the dissociation constant.

Mobility-Fixity Dimension in Witkin's Theory of Field-Dependence/Independence and its Implications for Problem Solving in Science

Various studies have shown the advantage of field independence for problem solving in science courses. The mobility-fixity dimension of Witkin's theory suggests that, although field-independent subjects are successful in science courses, field-independent subjects who ate mobile are expected to be more successful. Mobile subjects are those who have available to them both a developmentally advanced mode of functioning (field independence) and a developmentally earlier mode (field dependence). To test the hypothesis that mobile subjects would obtain a better performance than fixed subjects in freshman chemistry, mathematics, and biology courses, the Group Embedded Figures Test was used along with the Figural Intersection Test to classify subjects as mobile or fixed ( ns = 0–24 per group). As predicted, subjects' performance in chemistry, mathematics, and biology courses showed the advantage of the mobile group. Necessary is a replication with a larger number of subjects, inclusion in content of course tests of items requiring scientific analysis, and use of a psychometrically rigorous Figural Intersection Test.

Contemporary chemical essays: Dealing with the writing problem in a freshman chemistry course

Contemporary chemical essays: Dealing with the writing problem in a freshman chemistry course

Help program for failing students in the final six weeks of freshman chemistry

A study was undertaken to determine the value of offering extensive remedial help to those students who were failing the freshman chemistry courses. Students were offered six weeks of remedial classes, tutorial help, and multiple choice exercises covering those areas of the course in which failing students encountered problems.

A tape-slide freshman chemistry course for non-science majors

A tape-slide freshman chemistry course for non-science majors