Introductory College Chemistry Research Articles

O conceito de eletronegatividade na educação básica e no ensino superior

The goal of this study was to examine the means used by textbook authors to introduce, define, and explain the electronegativity concept in high school and introductory college chemistry textbooks. Results obtained showed that most textbooks lacked history precedence and did not deal with the conceptual understanding and manifesting a strong standardization of characteristics that, from our point of view, do not favor the teaching-learning of the electronegativity concept.

An Integrated Approach To Introducing Biofuels, Flash Point, and Vapor Pressure Concepts into an Introductory College Chemistry Lab

Students explore the fundamental chemical concepts of vapor pressure and flash point in a real-world technical context, while gaining insight into the contemporary societal issue of biofuels. Lab activities were developed using a closed-cup instrument to measure the flash point of various biodiesel samples. Pre- and post-tests revealed that the student’s grasp of the relationship between vapor pressure and flash point went from 46% to 91% after completing the lab and 76% of students responded that measurement of flash point helped them better understand the concept of vapor pressure. In the 3-h lab, students produce a small sample of biodiesel fuel and then evaluate the safety and quality of their product compared with a commercially available reference fuel that meets ASTM specifications. The experiment illustrates how fuel properties depend on the production process and the resulting composition and purity of the fuel product. The observed differences in fuel flash points provide for an introduction of the concepts of chemical quality assurance and quality control. The goal of this lab is to increase understanding of biofuels and associated chemical concepts that influence the properties of various renewable and fossil fuels.

Identifying Atomic Structure as a Threshold Concept: Student mental models and troublesomeness

Atomic theory or the nature of matter is a principal concept in science and science education. This has, however, been complicated by the difficulty students have in learning the concept and the subsequent construction of many alternative models. To understand better the conceptual barriers to learning atomic structure, this study explores the troublesome nature of this fundamental scientific concept. In order to illustrate the distinction of student understanding by threshold barriers, this study chose three particularly high‐achieving students from an original interview sample of 20 students who were selected from an introductory college chemistry course. The pre‐course and post‐course interview responses were examined and compared in detail. This study considers the concepts of ‘probability’ and ‘energy quantization’ to both describe the structure of the threshold of understanding students’ need to negotiate in their construction of the target model of atomic structure. In this respect, this study suggests atomic structure as a possible threshold concept for further study in science. Identifying the nature and structure of the threshold of understanding confronting students, and analyzing the troublesomeness of atomic structure, provides valuable information for understanding student learning difficulties, and insight into how they may be addressed.

The Two High-School Pillars Supporting College Science

Out-of-discipline high-school science courses are not associated with better performance in introductory college biology, chemistry, or physics courses, but high-school math counts.

High School Chemistry Instructional Practices and Their Association with College Chemistry Grades

This large-scale survey study looks for connections between high school chemistry classroom instructional practices and the performance of these students in introductory college chemistry. Based on survey data collected from over 3000 students in 31 different colleges and universities, the results indicate that students who reported higher frequencies of high school chemistry experiences such as peer teaching and “everyday” (i.e., common) examples, on the average, earned higher college grades. However, students who reported higher frequencies of demonstrations and individual work among other indicators, on the average, earned lower grades. Overall, the results suggest that peer engagement in high school chemistry may be associated with success in college chemistry.

Introducing New Learning Tools into a Standard Classroom: A Multi-Tool Approach to Integrating Fuel-Cell Concepts into Introductory College Chemistry

Bringing cutting-edge scientific research into the general curriculum can be challenging for educators at all levels. We describe an approach to deliver the science and engineering concepts involved in fuel-cell technology to the introductory college chemistry classroom. This approach includes using traditional lectures, multimedia learning objects, and a lab activity to enhance student learning in a hands-on, interactive manner. The learning objects and lab activity are both new learning tools and are implemented in a two-year college classroom. A simple, first assessment of this approach is described along with preliminary results from a second, more rigorous assessment. The potential to satisfy various learning styles is discussed based on feedback from students about the new learning tools. We also highlight the collaboration between several educational institutions and research and education programs that made the development and implementation of this unit possible.

High School Chemistry Content Background of Introductory College Chemistry Students and Its Association with College Chemistry Grades

Do students who focus on some content areas in high school chemistry have an advantage over others in college chemistry? Published research on high school preparation for college science dates back as far as the 1920s, but results have been mixed. This manuscript seeks to answer this question through the use of a broad-based survey of 3521 introductory college chemistry students. This study provides descriptive analyses showing the distribution of high school content experiences reported by college chemistry students from 31 four-year colleges and universities in the United States. The results indicate that stoichiometry rises above seven other topic areas studied in high school as most strongly predictive of college chemistry success. In addition, three mathematics background predictors, including calculus background, were found to be highly significant.

Traditional and Block Scheduling for College Science Preparation: A Comparison of College Science Success of Students Who Report Different High School Scheduling Plans

This study compares frequencies of instructional practices across differing scheduling plans (Traditional and Block plans), and explores the association between high school scheduling plans and college science preparation, using introductory college science grades as the outcome measure. More than 7000 students enrolled in introductory college biology, chemistry, and physics were surveyed. No large difference was found when comparing the use of frequencies of instructional practices across scheduling plans. Regression models investigating associations between scheduling plans and college grades found significant, but small differences in predicted college grades for Traditional, 4:4, and Unique Block students; however, the analysis found two negative interactions on college grades linking alternate Block (AB) with HS science achievement and AB block with peer tutoring. Overall, the results indicate that Block scheduling plans do not appear to provide an advantage to students in terms of college preparation in science.

Factors influencing success in introductory college chemistry

AbstractPrevious research has found a wide range of predictors of student performance in introductory college chemistry. These predictors are associated with both the students' backgrounds and their high school learning experiences. The purpose of this research study was to examine the link between high school chemistry pedagogical experiences and performance in introductory college chemistry while accounting for individual educational and demographic differences. The researchers surveyed 1531 students enrolled in first‐semester introductory college chemistry courses for science and engineering majors at 12 different U.S. colleges and universities. Using multiple regression analysis, the researchers uncovered several interesting high school pedagogical experiences that appeared to be linked with varying levels of performance in college chemistry. Most notably, the researchers found that repeating chemistry labs for understanding was associated with higher student grades, whereas overemphasis on lab procedure in high school chemistry was associated with lower grades in college. These results suggest that high school teachers' pedagogical choices may have a link to future student performance. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 987–1012, 2005

Template Synthesis and Magnetic Manipulation of Nickel Nanowires

In this experiment students prepare nickel nanowires using a template synthesis technique and characterize their properties. Electrodeposition of nickel to fill the 200-nm diameter pores of a commercially-available alumina filtration membrane is accomplished using a nickel salt solution and a AA battery. The nanowires, which are ~200 nm in diameter and up to ~50 μm in length, can be liberated from the membrane by dissolving the alumina template with sodium hydroxide. Suspensions of nanowires on a microscope slide can be observed using a common optical microscope. The alignment and movement of the magnetic nanowires can be controlled using magnets. This experiment is appropriate in introductory college chemistry courses and in upper-level physical and inorganic chemistry courses. The experiment provides students with a hands-on laboratory experience in nanotechnology, while illustrating fundamental ideas from a variety of areas, including electrochemistry, magnetism, and materials science.

What Defines Effective Chemistry Laboratory Instruction? Teaching Assistant and Student Perspectives

Although the chemistry laboratory is an essential element of the majority of introductory college and university chemistry courses, labs are often criticized for the lack of student learning that occurs. Research concerning teaching effectiveness indicates the factors involved in teaching effectiveness; however, most of this research focuses on classroom instructional methods. Our research identifies qualities that students and teaching assistants perceived to be important for effective instruction within the introductory university chemistry laboratory context. Students and teaching assistants involved with a large enrollment, introductory chemistry laboratory course were asked to complete a two-part questionnaire containing both Likert and free-response questions. Analysis of the questionnaires indicated good, though not complete, agreement between students and teaching assistants as to the qualities considered to be most important in determining effective instruction. A general picture of an effective introductory chemistry laboratory teaching assistant begins to emerge. This article discusses results of the questionnaire, possible implications these findings have for preparing chemistry laboratory teaching assistants, and directions for future work in this area.

Skill and will: The role of motivation and cognition in the learning of college chemistry

This study investigated how students' level of motivation and use of specific cognitive and self-regulatory strategies changed over time, and how these motivational and cognitive components in turn predicted students' course performance in chemistry. Participants were 458 students enrolled in introductory college chemistry classes. Participants' motivation and strategy use were assessed at three time points over the course of one semester using self-report instruments. Results showed an overall decline in students' motivational levels over time. There was also a decline in students' use of rehearsal and elaboration strategies over time; students' use of organizational and self-regulatory strategies increased over time. These trends, however, were found to vary by students' achievement levels. In terms of the relations of motivation and cognition to achievement, the motivational components of self-efficacy and task value were found to be the best predictors of final course performance even after controlling for prior achievement.

College Chemistry and Piaget: An Analysis of Gender Difference, Cognitive Abilities, and Achievement Measures Seventeen Years Apart

This study revisits an analysis of gender difference in the cognitive abilities of college chemistry students using scores from "Inventory of Piaget's Developmental Tasks" (IPDT), the Scholastic Assessment Test (SAT), and final grades from an introductory college chemistry course. Comparison of 1998 scores with those from 1981 showed an overall decline on most of the measures and a changing pattern among males and females. Gender differences were found in the IPDT subtests measuring imagery, classification, and proportional reasoning, but not conservation, a pattern that differs from the findings reported 17 years earlier. The generational and gender differences revealed in this study suggest that instructors should be cognizant of, and should periodically assess, the diversity of students' cognitive abilities.

Microscale Quantitative Analysis of Hard Water Samples Using an Indirect Potassium Permanganate Redox Titration

A microscale procedure for the volumetric determination of calcium in an unknown hard water sample is reported. The experiment is accomplished via quantitative filtration and collection of calcium oxalate, which has been precipitated from the unknown sample, followed by microscale titration of the free oxalate using standardized potassium permanganate. While designed for a quantitative analysis laboratory, this experiment should also be suitable for an introductory college chemistry laboratory. Also reported are test data for the procedure, as well as data acquired by quantitative analysis students. Comparison with previous macroscale data indicates that the microscale procedure can be performed with comparable accuracy and precision, though student data indicate that the microscale procedure suffers from determinate error, most likely from loss of calcium oxalate during the filtering stage. This error leads to potential under-representation of calcium in the unknown.

Using Limiting-Excess Stoichiometry to Introduce Equilibrium Calculations: A Discrepant Event Laboratory Activity Involving Precipitation Reactions

The transition between limiting and excess stoichiometry and equilibrium calculations is demonstrated in a laboratory activity for introductory college chemistry students. Students are presented with two precipitation reactions and asked to predict the identity of any excess reactants in the filtrate, on the basis of mole calculations they have already learned. They find that in one of the reactions there are two excess reactants instead of only the one that they originally predicted. This "discrepant event" provides a motivating laboratory opportunity in which to introduce the concept of equilibrium, equilibrium calculations, and Ksp as reasonable explanations of the results.

HELPING STUDENTS TO MAKE INFERENCES ABOUT THE ATOMIC REALM BY DELAYING THE PRESENTATION OF ATOMIC STRUCTURE

The presentation in many introductory college chemistry courses jumps around in an unsystematic fashion among the domains of macroscopic observation, sub-microscopic particles, and symbolic representation, making it difficult for students to construct a coherent picture of the discipline. Such presentations usually pay little attention to the intellectual struggle that led to fundamental knowledge in chemistry. Topics like atomic and molecular structure are often introduced early in the course, even though they are far removed from direct experience, and historically were elucidated relatively late in the history of chemistry. This paper describes a freshman chemistry curriculum, in which the topic of atomic structure is delayed until the second semester. Concept development is linked to the observable behavior of matter, while the sub-microscopic and symbolic realms are introduced by engaging students in some of the detective work that established the relative atomic masses of the elements and formulas of simple compounds. In this way, students have an opportunity to become familiar with the relationships among facts, definitions, hypotheses, deductions, and predictions, which are central to the enterprise of science. A brief review of literature dealing with relevant history and educational research is included. [Chem. Educ. Res. Pract. Eur.: 2001, 2, 183-202]

Fizzy Drinks: Stoichiometry You Can Taste

This Activity is suitable for a high school chemistry or introductory college chemistry lab. It shows a very practical use of stoichiometry--that of making a carbonated drink similar to the popular Fizzies tablets that are added to water. The ingredients used are unsweetened powdered drink mix, aspartame sweetener (or sugar), citric acid, and baking soda. The citric acid and baking soda, when in solution, react to form carbon dioxide gas. Students are first of all challenged to try to make the drink using trial and error. This generally leads to poor results, since too much of any one ingredient will produce an unpleasant taste. However, by examining the complete balanced equation and using stoichiometry, students can easily determine the correct ratios of citric acid and sodium bicarbonate, which makes for a great tasting fizzy drink.

An Investigation of Electrolyte Solutions Using a Simple Conductivity Apparatus

A student laboratory exercise in qualitative analysis has been developed to address student misconceptions associated with electrolyte and nonelectrolyte solutions. This exercise uses a previously reported, inexpensive, home-built conductivity meter to identify acid solutions. An additional short preparatory exercise provides students the opportunity to classify known solutions as strong, weak, or nonelectrolytes and gives students experience using a conductivity meter. These activities have been used successfully with both high school and introductory college chemistry students.

An Analysis of College Chemistry Textbooks As Sources of Misconceptions and Errors in Electrochemistry

The oxidation–reduction and electrochemistry chapters of 10 introductory college chemistry textbooks were reviewed for misleading or erroneous statements, using a list of student misconceptions. These misconceptions include the notions that the identity of the anode and cathode depends on the physical placement of the half-cell; half-cell potentials are independent of each other, meaningful, and measurable; electrons can flow through electrolyte solutions and the salt bridge; cation movement does not constitute an electrical current; electrodes have large net positive or negative charges that can be used to explain ion and electron flow; and electrolysis products cannot be predicted using standard reduction potentials. As a result of this analysis, we provide suggestions for chemistry instructors and textbook authors: simplifications such as always drawing the anode as the left-hand half-cell or only describing the flow of anions in electrolyte solutions and the salt bridge should be avoided; vague or misleading statements should be avoided; cell potentials should be calculated using the difference method instead of the additive method; simple electrostatic arguments should not be used to predict ion and electron flow in electrochemical cells; and all possible oxidation and reduction half-reactions should be considered when predicting the products of electrolysis.

Intermolecular Forces in Introductory Chemistry Studied by Gas Chromatography, Computer Models, and Viscometry

An experiment on intermolecular forces for first-term introductory college chemistry is presented. The experiment integrates traditional viscometry-based measurements with modern chromatographic analysis and use of computer-based molecular models. Students performing gas chromatographic (GC) analyses of mixtures of n-alkanes and samples that simulate crime scene evidence discover that liquid mixtures can be separated rapidly into their components based upon intermolecular forces. Each group of students is given a liquid sample that simulates one collected at an arson scene, and the group is required to determine the identity of the accelerant. Students also examine computer models to better visualize how molecular structure affects intermolecular forces: London forces, dipole-dipole interactions, and hydrogen bonding. The relative viscosities of organic liquids are also measured to relate physical properties to intermolecular forces.