Chemical Thermodynamics Exercise

[Qiana Thieklin]

Nrdu tilmelder dig kurset, skal du vre opmrksom p, om der er sammenfald i tidspunktet for kursusafholdelse og eksamen med andre kurser, du har valgt. Uddannelsesplanlgningen tager udgangspunkt i, at det er muligt at gennemfre et anbefalet studieforlb uden overlap. Men omkring valgfrie elementer og studieplaner som gr ud over de anbefalede studieforlb, kan der forekomme overlap, alt efter hvilke kurser du vlger.

When registering for courses, please be aware of the potential conflicts between courses or exam dates on courses. The planning of course activities at Roskilde University is based on the recommended study programs which do not overlap. However, if you choose optional courses and/or study plans that goes beyond the recommended study programs, an overlap of lectures or exam dates may occur depending on which courses you choose.

The course provides a broad introduction to chemical thermodynamics and kinetics. We discuss the most useful thermodynamic functions and kinetic models and see how they can be applied in practical examples from biochemistry, technical chemistry, and engineering.

Atkins' Physical Chemistry. Once you have an overview of the material you may turn to the book and read about the theory in more detail. It will often be an advantage to focus on topics where you need further explanation. The curriculum is defined by the pages in the study plan, but the most important material is presented in the lectures.

Exercises and problems. Before each class you should prepare the exercises/problems stipulated in the study plan. This is a very important activity, and you should spend the necessary time to complete the exercises. Towards the end of the course, we will work with old exams rather than exercises from the book.

Exam. The result at the written exam will count 67% towards the final mark while the rest comes from the data analysis reports. You will need to re-submit your Data analysis reports at the start of the exam, so please bring a copy.

The course includes formative evaluation based on dialogue between the students and the teacher(s) (as well as written feedback on the reports). The course is also evaluated through a questionnaire in SurveyXact (and oral evaluation at the end of the course). The Study Board will handle all evaluations along with any comments from the course responsible teacher.

The aim of this study was to apply current pedagogical research in order to develop an effective course and exercise structure for a physical chemistry thermodynamics course intended for second or third year university students of chemistry. A mixed-method approach was used to measure the impact the changes had on student learning. In its final form in 2014, the course consisted of lectures following a broken lecture structure that incorporated different kinds of activating learning tasks, and a three-tiered exercise structure including qualitative and quantitative tasks with a large emphasis on collaborative problem-solving. The new lecture and exercise structures improved student learning as measured by students' exercise points, exam results, and, between 2013 and 2014, the results of a conceptual thermodynamics test the students took at the beginning and end of the course. Even though the new exercise structure increased students' motivation, positive affect and satisfaction with the course, in both 2013 and 2014, it was the interactive lecture structure that students reported to be the most beneficial part of the course. In light of these results, this study demonstrates the advantages on student learning of adopting a multifaceted approach to both lectures and exercises.

The continuation of a two-semester sequence covering the fundamental principles and applications of chemistry designed for science majors. Topics to be covered include intermolecular forces, properties of solutions, chemical kinetics, chemical equilibrium, chemical thermodynamics, and electrochemistry. Laboratory exercises supplement the lecture material.

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Thermodynamics is a classic scientific discipline of singular logic and rigor, the results of which are of great general applicability. Chemical thermodynamics deals more specifically with phenomena such as phase transitions, reactions, and changes in noncovalent structures. The approach of thermodynamics is to make a distinction at the outset between the part of the universe that is to be studied, which is denoted the system, and everything else. This "everything else" in the in the universe is designated as the surroundings. The system is separated from the surroundings by a boundary, the properties of which are further specified. The boundary may be imaginary or it may correspond to a physical barrier.

We can envision different types of boundaries and permitted exchanges between the system and surroundings. One of particular interest to us is a closed system in which no matter is exchanged. We further specify that it is possible for the system to exchange energy with the surroundings, so that the system is closed, but not insulated. Therefore it is possible for heat to be exchanged. In addition, the system may do work on the surroundings or vice-versa. In the former case, the system gives up energy to do the work on the system, while in the latter case, the system acquires energy by virtue of the surroundings doing work on it. In any case, the energy gained or lost by the system must be exactly balanced by the loss or gain of energy of the surroundings. This is simply a consequence of the law of conservation of energy (also often referred to as the first law of thermodynamics), which we discuss more formally below.

As an example of a system relevant to chemistry, we may be interested in the system of a gas phase reaction within an enclosed volume. Here, the system is closed but not necessarily isolated. A truly isolated system would require a boundary that does not conduct heat - a perfect insulator - and no such material exists. However, there are reasonably good insulators, such as the walls of a thermos bottle, and over a relatively short period of time only a very small amount of heat is transferred to or from such an insulated system. A chemical reaction taking place in a solution contained in a beaker on a laboratory bench can also be treated as a closed system, at least if no gases are produced or consumed in the reaction, and if our critical observations are made on a time scale over which evaporation of solvent is insignificant.

In developing thermodynamic principles, much use is made of isolated and closed systems, and the emphasis is placed upon equilibrium conditions. Ultimately, however, in a thermodynamic analysis of biological systems, we are forced to consider that living organisms constitute open systems that exchange matter and energy with their surroundings. Furthermore and remarkably, as systems living organisms are not at equilibrium, but instead are autonomous systems that generate and control flux of matter and energy through them to maintain a nonequilibrium steady state.

The idea of the state of the system is fundamental. The state is determined by specifying all relevant state variables, namely the chemical composition (moles of substances 1, 2,..., i), as well as the temperature (on an absolute scale, i.e. in kelvins, K), pressure, and volume. Defining the state of the system will also determine the total internal energy, a thermodynamically important quantity that we'll examine more carefully below. If we have in mind either of the chemical reaction examples, the reactants at a certain temperature, pressure, and volume will correspond to an initial state of the system. In the final state - at the end of the reaction - products will be present at some final T, P, and V. It may be most convenient if these values are the same as the initial T, P, and V and if the system under consideration can be treated as closed. This allows us to focus on the energetics of the chemical reaction alone and simplifies the theoretical analysis. Perhaps our single most important goal in studying such systems of chemical reactions is to understand that the process by which they spontaneously approach the state of equilibrium is determined by progress toward a minimum of a thermodynamically defined function of the state of the system called the free energy.

Classical thermodynamics deals with macroscopic systems, those we can readily observe and measure in the laboratory. The state variables temperature (T), pressure (P), and volume (V) are of course quantities subject to measurement, and we employ the mole as a unit of measurement for the amounts of different substances present in the system. Strictly speaking, though, the methods and results of thermodynamics are independent of the molecular and atomic nature of matter. (We could have chosen masses of the chemical components of the system.)These state variables are not all independent. For example, we know that in general, the volume of substances increases with temperature. In fact, there is an equation of state that expresses mathematically the interdependence of the state variables. In the case of an ideal gas, which we discuss further below, an explicit equation of state is the well-known ideal gas law, PV = nRT.

When we study specific systems we are interested in processes, such as chemical reactions, where the system undergoes measurable change. We can define the changes a system may undergo in the formalism of thermodynamics. By change of state, we mean any change from an initial state, specified by an initial set of values of the state variables, to a final state. The final state is, of course, specified by its own set of values of the state variables. Considering the number of state variables, there may be innumerable processes that begin and end with a specified pair of states. The path specifies exactly how the state variables change for a given process starting at an initial state a and ending with a final state b. The path can be thought of mathematically as a curve in n-dimensional space. Although we can imagine an unlimited number of such curves, any equation of state will constrain the possible paths. In practice, we consider a limited number of processes of special interest or usefulness.

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