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The Gouy–Stodola theorem of thermodynamics is probably the most important one from an engineering point of view. It is indispensable in the analysis and design of a process from a thermodynamics perspective. It quantifies the level of irreversibility in the process. Yet, it has not received the due attention in the engineering literature. For example, the textbooks in chemical engineering thermodynamics rarely mention this theorem. This theorem can be expressed in two different ways, either in the form of exergy destruction or in the form of lost work. The conditions under which this theorem is applicable are not clearly spelled out in the existing textbooks and published literature. There is confusion in the literature regarding the general validity of the theorem. In this article, a complete analysis of this theorem is presented for open systems and its limitations are pointed out. This article should be of help to students in understanding and applying the Gouy–Stodola theorem to different practical situations dealing with flow processes. Due to its practical significance, it is important that this theorem is taught to all engineering undergraduate students regardless of their engineering discipline. As the theorem involves advanced level concepts in thermodynamics such as entropy generation and exergy destruction in the system and the surroundings, the appropriate place for the introduction of this theorem is the second advanced-level course in thermodynamics. This should not pose any problem as most engineering disciplines teach two one-semester courses on thermodynamics to the undergraduate students. [ABSTRACT FROM AUTHOR]

Students learn when they connect new information to existing understanding or when they modify existing understanding to accept new information. Most current teaching methods focus on trying to get students to solve problems in a manner identical to that of an expert. This study investigates the effectiveness of assessing student understanding related to context specific problem solving decisions, prescribing feedback based on the assessment, and improving student understanding to the point where they can make correct decisions. Students were given a refrigeration problem unlike their prior problems and were asked to draw the cycle on a T-v diagram using a tutor system. Every group tested (a total of 373 students) showed a significant improvement in their understanding (p<0.0001, Cohen's d>0.8) using a single 40 minute tutor activity. [ABSTRACT FROM AUTHOR]

The utility of Just-In-Time-Teaching (JITT) is compared across course topics and groups of students not receiving JITT exercises in class. JITT feedback incorporated various active learning exercises based on students' performance on online homework problems from Sapling Learning. With over 200 students in two sections participating in the sophomore level introductory thermo-dynamics course, student performance was evaluated on in-class quiz and exam problems. Student performance covering a specific course topic subsequently reinforced by a JITT exercise was found to be measurably higher (>9%) than a control group who did not receive the JITT review. Overall, comparing student achievement across five topics covered by JITT compared with five different course topics not covered by JITT did show small positive outcomes. The improvements after using JITT exercises included a higher median and 3rd quartile scores, so JITT may be beneficial to mid-performing students. Overall, student feedback on the JITT reviews showed that over 85% of the students thought the JITT exercises were helpful for engagement and a good use of class time. [ABSTRACT FROM AUTHOR]

Thermodynamics is a particularly challenging course for many engineering students early in their college education. Thus, it represents a significant opportunity for the use o f concept inventories to assess students' understanding o f core ideas and principles in order to gauge their initial knowledge and aid their future learning. In this paper we forward an inventory to assess students' understanding o f foundational thermodynamics concepts and principles, such as state relations, heat, work, and conservation o f energy, as well as their ability to reason conceptually using this knowledge. A 36-item thermodynamics conceptual reasoning inventory (TCRI) was developed and evaluated. The inventory was reviewed by four external experts and administered to 448 students. This study reports evidence to demonstrate th a t TCRI scores are a reliable and valid indicator o f students' thermodynamics conceptual knowledge and reasoning ability. TCRI scores show high internal consistency, distinguish between cohorts expected to differ, and correlate with course assessments. The TCRI is recommended for students beginning their study o f thermodynamics. Course instructors can use the T C R 1 as a formative assessment. The TCR I can also serve as an assessment tool for researchers to evaluate the effects o f instructional interventions. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to present an introductory course in chemical engineering based on analogies and researchbased activities. The use of analogies can be a very helpful tool used to build a strong engineering foundation for freshmen with weak high school scientific background. To help students shift from the imaginary of the five analogies utilized in the course to the real pictures of some engineering concepts, the similarity to the analogy is followed by simple lab experiments or class activities. The final chapter of this course is related to energy efficiency to demonstrate to freshmen who lack scientific background that their attitude could make them more efficient and lead them to success. [ABSTRACT FROM AUTHOR]

In this study, we measured chemical engineering students' response times to multiple choice thermodynamics concept questions while the students were engaged in technology-facilitated active learning in class. We examine response time differences for over 12,000 responses: between correct and incorrect answers, with and without written explanations to justify the answers, and as a function of question difficulty. For students who wrote a written explanation, we also investigated the length of explanation. We are interested in both implementation issues for the practitioner and in contributing to the extant understanding of the ways in which these type of question influence student thinking processes. Our findings show that students who answer correctly take less time to answer easy questions than those who answer incorrectly, but more time for more difficult questions. Response times are correlated with question difficulty when the correct answer is chosen, but not for incorrect answers. Moreover, for easy questions, explanations that are correct are likely to contain more words whereas for more difficult questions explanations associated with incorrect answers contain more words. When accounting for difficulty, it takes students about 100 seconds longer to provide a written explanation justifying their answer choice. However, differences in response data suggest that students who justify their answers in writing also more commonly activate thinking processes that focus on domain-specific knowledge. When possible, we advocate using written explanations in conjunction with multiple-choice concept questions during active learning in class, arguing that the short additional time needed to allow students to type explanations activates more deliberate thinking processes. [ABSTRACT FROM AUTHOR]

Thermodynamics is a fundamental foundation of all engineering disciplines. A vast majority of engineering undergraduate programmes contain one or more courses on thermodynamics, and many engineers use thermodynamics every day to analyse or design energy systems. However, there is extensive anecdotal evidence as well as a wide range of published literature indicating that students often struggle to understand thermodynamic principles. In an effort to understand students' attitudes and perception of thermodynamics, including their expectations, experience and frustrations, an investigation was conducted. Following a review of the literature on the teaching and learning of thermodynamics in engineering, a survey questionnaire was developed and administered to close to a 1000 students in 17 thermodynamics classes at 13 universities in 7 countries. Survey results were analysed using statistical methods. This paper presents the findings of this investigation. [ABSTRACT FROM AUTHOR]

We demonstrate that the formula for irreversible expansion work in most chemical thermodynamics textbooks does not apply during the expansion process. Instead of the "external pressure" Pext, the pressure Psys,mb on the piston or other moving boundary (hence the subscript mb), which is nearly equal to the system pressure Psys, should be used in the integral over volume. This formula only requires that Psys(V) and T are well defined, that is, a system of uniform P and T ("uPT") undergoing a "uPT process", which may be irreversible. An instructive example is an expanding gas accelerating a bullet horizontally and performing work without a conventional external pressure. We emphasize that δw = -Psys,mb dV ≈ -Psys dV is the only useful formula for infinitesimal PV work during a uPT process. The quasistatic approximation Psys,mb = Psys and δw = -Psys dV is usually excellent and enables analyses of irreversible uPT processes, for example, in heat engines; friction in the surroundings and a large piston mass improve the approximation. Slow chemical reactions at constant T and P are quasistatic, and many equations in advanced chemical thermodynamics apply specifically to uPT or quasistatic processes. We show that the equality dS = δqirr/T applies in irreversible quasistatic processes without composition change. In short, with well-defined P and T at constant composition, the simple equations for reversible processes are usually excellent approximations even when the process is irreversible. [ABSTRACT FROM AUTHOR]

The fundamental criteria for chemical reactions to be spontaneous in a given direction are generally incorrectly stated as ΔG < 0 or ΔA < 0 in most introductory chemistry textbooks and even in some more advanced texts. Similarly, the criteria for equilibrium are also misstated as being ΔG = 0 or ΔA = 0. Following a brief review of the thermodynamic equations related to reaction spontaneity and equilibrium in systems involving a single reaction, this paper addresses the nature of these errors by first discussing the conceptual problems thereby introduced. This qualitative discussion is followed by a quantitative treatment of the 2NO2(g) → N2O4(g) reaction conducted both under constant temperature and volume and under constant temperature and pressure conditions. The results provide clear examples of the conceptual problems introduced by using ΔG < 0 or ΔA < 0 as criteria for reaction spontaneity and ΔG = 0 or ΔA = 0 as the corresponding criteria for equilibrium. It is shown that ΔG < 0 or ΔA < 0 are necessary conditions for a transformation from state A to state B to be spontaneous, but they are not sufficient conditions. If ξ denotes the reaction coordinate, the correct criteria for a spontaneous forward reaction are (∂G/∂ξ)T,p < 0 or (∂A/∂ξ)T,V < 0 when the process can be characterized by a single reaction coordinate. The correct criterion for equilibrium is either dG = 0 or dA = 0. The paper concludes with some briefly stated recommendations as to the manner in which textbooks should be altered. The pedagogical problem of presenting the correct criteria for spontaneity and equilibrium to beginning students not versed in calculus and thermodynamics is also addressed, and some recommendations are made. [ABSTRACT FROM AUTHOR]

We describe how complex concepts in macroscopic chemistry, namely, thermodynamics and kinetics, can be taught at considerable depth both at the first-year undergraduate as well as upper levels. We begin with a careful treatment of PV diagrams, and by pictorially integrating the appropriate area in a PV diagram, we introduce work. This starting point allows us to elucidate the concept of state functions and nonstate functions. The students readily appreciate that for a given transition, the area enclosed by the PV curve (work) depends on the path taken. It is then are used that heat, within this chosen framework, is a consequence of energy conservation and the fact that work is not a state function. This leads to a visual introduction of all the components involved in the first law of thermodynamics. The PV diagrams are then used to introduce entropy as being related to the maximum possible work to be done by the system. This macroscopic description of entropy is then related to the usual microscopic view of Boltzmann. This equivalence connects the area inside the PV diagram (work from a specific kind of pathway) and the number of microstates involved in the Boltzmann expression. The connection between the macroscopic and microscopic description of entropy also illuminates the exponential dependence of the number of microstates (or probability) on an energy, known as free energy. The Arrhenius picture of chemical kinetics then readily follows from the exponential dependence stated above, and finally, a reactive event is viewed as a statistically rare event, to further clarify the appearance of entropy in the rate expression. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols represent an interesting and practical way for students to learn about chemical thermodynamics. This paper describes a laboratory experiment designed for physical chemistry students in which they learn about phase transitions of salt aerosols. The aerosols are generated by atomizing a salt solution, and then they are passed through a gas cell in a transmission-mode Fourier transform infrared spectrometer. Utilizing the O-H stretch of liquid water, the relative quantity of water in the aerosols can be measured. The deliquescence phase transition in which the solid aerosol particle dissolves to form a liquid droplet is evidenced by an abrupt increase in the water content of the aerosols. Multiple salts are suitable for analysis, including sodium chloride and ammonium bisulfate. Additionally, comparisons to model calculations can be made using the Extended Aerosol Inorganics Model Web site. This lab exposes students to important thermodynamic concepts such as chemical potential, activity, and phase transitions and forces them to critically interpret spectra. [ABSTRACT FROM AUTHOR]

The article presents an overview of the Marcus Theory for use in undergraduate general and introductory chemistry courses. The theory asserts that electron transfer reaction kinetics are subject to thermodynamic effects when they occur in solution. Topics include the redox enzyme reaction, the relationship between reorganization energy and activation free energy, and reaction cell potentials.

The article looks at a laboratory experiment for an undergraduate general chemistry course to study the thermodynamics of the reaction between cobalt chloride isopropyl alcohol and methanol to form cobalt chloride isopropyl alcohol methyl alcohol. The exercise measures the equilibrium constant to determine Gibbs energy, entropy and enthalpy of the reaction. Instruments used in the experiment include a datalogger, colorimetric sensor, and temperature sensor.

This letter calls attention to the coverage of kinetic metastability in the introductory textbooks and accompanying online materials written by the author and his coauthors. [ABSTRACT FROM AUTHOR]