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MERLOT II


    

Peer Review


2nd Law of Thermodynamics

by Frank Lambert
 

Ratings

Overall Rating:

4 stars
Content Quality: 4 stars
Effectiveness: 3.5 stars
Ease of Use: 4.8 stars
Reviewed: Jun 08, 2005 by Chemistry Editorial Board
Overview: An excellent tutorial for the simulation of the 2nd Law of Thermodynamics.
The material covered by the tutorial discusses the law microscopically and
macroscopically by way of a bouncing rubber ball. A rubber ball is represented
as a series of interconnected springs. The ball is released from a height. As
it bounces, the gravitational potential energy is gradually converted via.
kinetic energy to internal energy associated with motion of the sets of springs
holding the 'ball' together.
Learning Goals: The aim here is to demonstrate with a model system the second laws of
thermodynamics.
Target Student Population: First year students will benefit from studying this animation as will advanced
high school chemistry and physics students since the material is conceptual in
nature and is therefore suitable to all student populations.
Prerequisite Knowledge or Skills: It will help the student if he/she has a very basic understanding of
intermolecular forces and interactions and some introductory understanding of
the laws of thermodynamics.
Type of Material: This is a robust interactive applet.
Recommended Uses: This applet could be well used for helping students understand the concepts of
the irreversible conversion of energy and the first two laws of thermodynamics.
Technical Requirements: The browser MUST support JAVA applets. Users are advised to read the directions
for using the simulation and the accompanying material before or while working
with the simulation.

Evaluation and Observation

Content Quality

Rating: 4 stars
Strengths: The author's stated goal: "So one way to interpret what you see in this little
simulation is that energy initially present as an overall bouncing or falling
motion of a ball does not vanish as the ball bounces, but is rather transformed
into heat: each time the ball bounces lower it gets simultaneously hotter." is
well met. Care should be taken to provide users with necessary documentation and
background information on the First Law of Thermodynamics.


Concerns: It would be very helpful if dynamic graphs were presented which showed
gravitation potential energy, kinetic energy, and internal energy and the sum of
all three simultaneously. This would help in explaining the energy conversion
process and showing how the model demonstrates so very well the first two laws
of thermodynamics. Presently the discussion is minimal but adequate.

Potential Effectiveness as a Teaching Tool

Rating: 3.5 stars
Strengths: This is a magnificent interactive demonstration of energy conversion and the
process of 'heating' etc. Thermodynamics is generally hard to teach
conceptually. This applet helps to solidify those concepts which are too hard
to students to grasp abstractly by providing a suitable mechanical model for
discussion. In addition the introduction of the statistical basis of the Second
Law is especially nicely presented.


Concerns: Some parts of the discussion suggest that degrees of freedom store heat energy
rather than motion. This could lead to confusion for the student. It would be
good if something like: "We use degrees of freedom to discuss the motion of a
system and the fundamental molecular, atomic and/or ionic units that comprise
the material making up that system". Further the statement: " The Second Law of
thermodynamics states in effect that no matter how carefully you channel energy
from one macroscopic degree of freedom to another, some of it is bound to leak
away as heat, that is, wander off into the microscopic degrees of freedom and
get lost." might be better worded as: "The Second Law of thermodynamics states
in
effect that no matter how carefully you channel energy from one macroscopic
degree of freedom to another (e.g., potential to kinetic, etc.), some of that
energy is bound to be converted into heat energy which is stored as microscopic
motion within the material." In addition, the failure to present the energies
available in a conveniently viewed and summarized graphical form leaves the
student without a ready way to grasp that energy is conserved and that disorder
is increased. Graphs are imperative to convert this page to a first rank page
for use in freshman chemistry and physical chemistry undergraduate discussions.

Ease of Use for Both Students and Faculty

Rating: 4.8 stars
Strengths: The applet is VERY robust, loads quickly and works well. The software provided
excellent feedback, and was generally easy to operate except for the energy bar
graphs.


Concerns: The user doesn't really have a good feeling or understanding about where the
sliders should be on the right hand side of the applet. When the user clicks on
the energy button, the energy graphs which are presented tend to flash by.
Furthermore, the graphing window disappears when the user clicks on it, it
doesn't appear as a top window and is poorly labelled. Also for some reason the
energy bar graph is hard to put on and stay on once the program was started.
This could be attributed to either the Applet or the browser.

Other Issues and Comments: This simulation applet is nicely done and the accompanying discussion provides
significant conceptual understanding of both the First and Second Laws. The
introduction of a statistical basis for the Second Law is especially nice. The
graphing of the energy is plagued with usability difficulties and doesn't
clearly present the concepts the author wants to present. The secondary graph
has a tendency to flash on and off when the main 'energy' button is pressed.