| HOME |
Thermodynamic Equilibrium |
|
|
|
Reviewer: Marjorie Klenin
Comments: General quality: *** (3 stars)
This package provides a nice graphic representation of thermal equilibrium. It shows that the "temperature" of a gas involves not just the speed of the molecules, but also particle number. Approach to thermal equilibrium involves changes in both quantities. The seven experiments are well chosen to contrast different physical situations, and the questions are generally well phrased -- with the caveats, indicated below.
The level is appropriate for upper level high school or for an elementary college chemistry or physics course. It could be used either as a classroom or laboratory demonstration, or as the basis of a written assignment.
Ease of use: **** (4 stars)
The package is complete and ready to use, and the instructions are clear and concise. The authors have gone to some trouble to point out technical requirements; these are not overly restrictive. There are some apparent errors; these should be corrected by the authors, and until they are fixed, preparation of the assignment for student use does require some work on the part of the instructor.
Effectiveness: *** (3 stars)
All of the "experiments" are based on a single applet package with different initialization parameters. It would greatly improve the quality of interactivity if students were able to set the initial conditions themselves. It is apparently possible to set initial temperatures, but not the number of particles in each chamber.
The thermometers should be larger, and the scales should be friendlier. In fact, it is possible to start and stop the equilibration process, and more readable thermometers would make it possible to do some quantitative "experiments".
A stop watch on the experiment's panel, would also greatly enhance the package's value. I see no way to answer some of the questions posed in the absence of such an object.
In summary, the applet itself, with some minor modifications, could be a highly flexible teaching tool. The complete package does not make the most of its potential, and the resulting module is rather static. More interactivity would make it more engaging.
Quality control problems:
Thermom. scale is kind of peculiar. On my screen (tried both 1152 x 864 px and 800 x 600 px) the numbers are truncated, and illegible. Two of the questions under E1 are not answerable.
Q:Why are there more particles in the cold side than the warm side when you first start mixing the chambers?
It isn't obvious to me that there are. (Didn't actually try to count them, but if I believe the numbers, there are 100 on each side.)
Q:How long does it take for the temperature to equilibrate?
Can't see a reasonable way to answer this -- especially because of operational problems indicated by authors.
A more interesting question would be how the speed changes as equilib is approached.
Some of the authors' dire warnings about performance did not apply on the machine I used. It was not necessary to clear the browser cache, and there was no interference from other activities going on.
Reviewer: Bruce Mason
Description: This material uses a java simulation of the motion of the atoms in an ideal gas in two connected containers to demonstrate the approach to thermodynamic equilibrium. The containers are initially isolated with different temperatures and/or number of particles. A shutter between the containers can be opened and the temperature and number of particles in the two containers are shown as a function of time. There are 7 different simulations with different (and increasingly more sophisticated) initial conditions. There is also a "Maxwell Demon" game for students to try to remove the system from equilibrium.
Quality: Very Good
The material covers a very important topic in Thermodynamics. It demonstrates the meaning of equilibrium for an ideal gas as it relates to temperature and pressure. The simulation is accurate in the final equilibrium state it approaches, and also gives some ideas of fluctuations about equilibrium.
Usability: Good
The interface is clean, simple, and easy to understand. There is little to control so students will have no trouble running the simulation themselves. Unfortunately, there is no control over the initial state of the system so that users are limited to the simulations presented. More limiting, there is no recording of the time dependence of quantities such as Temperature, Pressure, and Density as the system approaches equilibrium. This would be useful to demonstrate such concepts as rates and fluctuations. This is not stand-alone material because it contains no material describing the physics being demonstrated.
Effectiveness: Very Good
As a qualitative demonstration of equilibrium, this would be material that students could use independently to get ideas about thermodynamic processes. I feel it would be effective in building conceptual understanding for students. Students could easily run the applet on their own. Because of the lack of quantitative time-dependent information, this material couldn't be use for something like a virtual experiment. In addition, it will need to be supplemented with standard reading material to explain the physics involved, but would be a useful addition to just about any treatment of thermodynamics.
Reviewer: Chris Wozney
Description:
A single applet shows two chambers of identical particles behaving as ideal gases separated by a removable partition. When the wall is removed, the particles mix and the current temperature on each side of the wall is displayed. The initial number of particles in each chamber and their temperatures are parameters of the applet. The site consists of seven experiments representing different initial conditions for the simulation.
Quality: excellent
This investigation is able to visualize concepts of thermodynamic equilibrium and many of the factors that affect thermal equilibrium in a simple, logical, and direct manner. Students engaged in these activities should have a better understanding of the microscopic theory of heat as well as the Second Law of Thermodynamics.
Usability: excellent
The applet works well, controls (buttons,etc.) Are minimal and necessary, and the meaning of the visuals is clear.
Effectiveness: excellent
The questions accompanying the experiments are direct, to the point, and pertinent to the concepts being presented by the simulation.
Possible Learning Objectives / Concepts:
Personal Comments
This set of on-line activities can be of great benefit for any instructor attempting to explain the microscopic meaning of the second law of thermodynamics. The questions asked with each applet are almost intuitively obvious; and yet, after making the coorect prediction, the student still has to logically justify the result. Students, therefore, build their own knowledge and understanding of the microscopic meaning of heat and temperature.
Experiments 6 and 7 are especially appropriate for a statistical physics / thermodynamics course. I have never before seen an interactive simulation where the students get to play Maxwell's demon. I would recommend this experiment for any class in which the concept of Maxwell's demon arises.
Recommended Applications:
In-class demonstration: not recommended
Given of the design of the site as seven experiments and the quality and simplicity of the questions asked for each experiment, this application will not be most effective as an in-class demonstration .
In-class guided activity: not recommended
The number of experiments and the nature of the questions require more time for observation and analysis than allowed for in most classes. However, use in a lab setting where more time is available is possible.
Out-of-class exploration: recommended
Students should enjoy completing these experiments and answering the questions if given as an out-of-class exploration. They will also gain a better intuitive understanding of the nature of gases, temperature, and calorimetry after visiting this site. Recommended if time constraints or course priorities prevent presenting this site as a homework assignment. (Note: unless some type of proof is required that the site was visited, most students will not complete a voluntary assignment.)
Homework assignment: highly recommended
The site, experiments, and questions are already designed for quick, homework-style answers. Prediction of outcomes (time, temperature) are within the scope of all students. The addition of some follow-up or summary questions to those given in the simulation is recommended. An in-class review of the simulations and the physics principles demonstrated by the applet after the assignment is complete should be worthwhile and is also highly recommended.
Individual use vs. small group: either method is appropriate.
Reviewer: Brian Box
Level of Material: introductory physics - algebra and calculus
Quality: Very good
This simulation represents the process of two gases reaching a state of thermodynamic equilibrium. A barrier is initially separating the two chambers containing the two gases, which are at different temperatures and number of particles. The barrier can be removed, which will allow you to observe the temperature changes and the number of particles in each chamber as the gases mix together. The simulation does a very good job of showing how the final temperature of a mixture is dependent upon not only the initial temperature of each chamber, but also the number of particles in each chamber just before the barrier is removed.
Usability: Very Good
The instructions are very clear and easy to follow. The author even points out the problem you may have with how Netscape or Explorer uses the cache, and how you can solve the problem. I personally did not any problems with the cache. The controls on the simulation frame are easy to use, and the simulation behaves, as it should when manipulated by the user.
Effectiveness: Very Good
The best usage of this simulation would be as part of a homework assignment to provide a better conceptual understanding of the equilibrium concept. The students would go through the first activity, and then they have to apply their new knowledge to several new situations with changes in temperatures and number of particles. The instructor may want to provide an initial introduction to help ease the students into exploring thermodynamic equilibrium.