Entropy Evaluation Information Page
Johnstone's Triangle Elements
Gas Law Specific Criteria
| Element | Examples |
|---|---|
| Macroscopic | Examples of phase changes (e.g., ice melting, water freezing). Demonstrations of entropy changes in physical and chemical processes (e.g., mixing of gases, dissolution of salts in water, dispersal of dye in water, increase in volume of a gas, dispersion of gases in combustion reaction). To be classified as a macroscopic example there must be some kind of explicit connection to entropy. Just saying that bananas rotting is driven by entropy is not enough. |
| Symbolic | Chemical equations showing entropy changes (e.g., phase changes, reactions). Graphs or diagrams illustrating entropy changes (e.g., Boltzman distributions graph, entropy vs. temperature graphs, energy distribution diagrams). Equations involving entropy (e.g., ΔS, ΔG = ΔH - TΔS). |
| Particulate | Particle diagrams showing the distribution of particles in different states (e.g., solid, liquid, gas). Illustrations of increased number of different arrangements at the particulate level (e.g., mixing of different colored particles to represent mixing of gases, or showing particles with different speeds/energies or positions/orientations). Note: particle representation of balanced chemical equation does not count here. |
| Connection between levels |
Videos should make explicit connections between two or more levels for this to be coded as present. For example, they could show a macroscopic example of a gas expanding and connect it to particle diagrams showing increased disorder and symbolic representations of entropy change.
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Core Ideas
| Core Ideas Elements | ||
| Change and Stability in Chemical Systems | Particulate Nature of Matter | Energy |
|---|---|---|
| Energy and entropy changes, the rates of competing processes, and the balance between opposing forces govern the fate of chemical systems. | Matter is comprised of individual particles and it is through interactions of these individual particles that materials exhibit their properties and undergo chemical reactions. |
Entropy is related to the distribution of energy. The more ways energy can be dispersed, the higher the entropy.
Increase in temp = increase in entropy |
Video needs to include:
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Video needs to include:
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Video needs to include:
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Casual Mechanistic Reasoning
Must have Both How and Why!
Option 1.1: What causes entropy changes in a system?
How: Increasing temperature will result in greater dispersal of energy.
Why: Increased temperature results in more energy levels/energy states being accessed which allows for more potential ways to disperse the energy.
Option 1.2: What causes entropy changes in a system?
How: Reactions can change the number of particles.
Why: A greater number of particles will increase the number of possible arrangements/positions (increase number of microstates) which allows for greater dispersal of matter. (or vice versa)
Option 1.3: What causes entropy changes in a system?
How: Phase changes and mixing of compounds will result in changes of volumes that particles can move in.
Why: Larger volumes allow for a larger number of possible positions/arrangements for particles (which leads to more microstates). This results in greater entropy for mixed systems or for gases over liquids over solids.
Option 2: What is the effect of molecular complexity on entropy?
How: More complex molecules have more possible ways to arrange their atoms and bonds, leading to a higher number of microstates.
Why: The increased number of microstates corresponds to higher entropy because there are more possible configurations for the particles. Complex molecules contribute to greater disorder due to their varied structures.
Option 3: What is the role of entropy in causing chemical/physical processes to occur?
How: In spontaneous processes the entropy of the system increases.
Why: When energy is more evenly distributed/dispersed among particles, the system is more stable. [I.e., more particles = greater potential to disperse energy; more flexibility = greater potential to disperse energy] OR there is a higher probability that the system will be in a state where energy is most evenly distributed
Scientific Practices
| Most Frequent Science Practices |
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SP 2: Developing and Using Models
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SP 4: Analyzing and Interpreting Data
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SP 5: Using Mathematics and Computational Thinking
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SP 6: Constructing Explanations and Engaging in Argument from Evidence
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Multimedia Principles
Multimedia learning as knowledge construction: The goal of multimedia presentations is not only to present information but also to provide guidance for how to process the presented information – that is, for determining what to pay attention to, how to mentally organize it, and how to relate it to prior knowledge. We will categorize the videos along each of the following criteria (High and Low should be mutually exclusive.)
| High | Low |
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Misleading vs. Inaccuracies
Analogies
Analogies vs. Macroscopic Example
Physics/Chemistry Definition of Microstate a specific arrangement or configuration of all the individual particles (atoms, molecules, etc.) within a system at a particular instant in time. It’s a snapshot of the system at the most fundamental level, detailing the precise locations and energy levels of each particle. Macrostate is physical property.
Examples of ball rolling down hill and not rolling all the way back up because of loss of energy to friction, air resistance – transfer of energy to surroundings.
Analogies Include:
A messy room which if approached from the perspective of only a few ways to arrange an ordered room but many ways to arrange disordered room is fine but if approached from ordered room is low entropy and messy room is high entropy then saying misleading.
Using results of multiple dice was deemed an analogy total of 2 dice = macrostate and individual ways to get to each some = “microstates”
Misleading
Describing entropy exclusively as randomness was not labeled as misleading, even though it is an inaccurate and incomplete interpretation of entropy.
Example High Quality Videos
These are examples of videos that were found to provide good illustrations of some or many of the framework components for this concept. Develop a deep understanding of chemistry concepts requires multiple experiences with the material and these videos may provide one such experience.
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Exemplar Video 1 |
Exemplar Video 2 |
Exemplar Video 3 |
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Comments Starts with messy room analogy and says while it is easy to see and understand, it is misleading. Prior knowledge: energy is quantized and definition of system and surroundings. Learning Objectives: Describe the concept of a microstate and discuss what entropy measures conceptually. Examples of spontaneous processes - definition. Gives pictures of spontaneous processes. Specific example - inflated balloon that has not been tied and is then let go. Gas that was in the balloon is now dispersed. Then food dye dispersing in water. Then hot pan cooling. 2nd law. Defines it in words and symbols. Measure of the number of ways energy can be distributed in a system of molecules. Uses dice analogy to talk about microstates (ways you can get to) for each macrostate (sum of 2 dice). Heat transfer example - one heated to 60°C and the other at room temperature. When you push them together, they equilibrate. Shows thermal imaging and connects this to the 2nd law equation. |
Comments Started with looking at dye dissolving in water through an analogy, then moved to actual dye. Followed up with a good example of how dye molecules will be more likely to disperse based on probability, including with Boltzmann calculations. Hit on how temperature impacts entropy. Discussed how systems might get more ordered (e.g., water freezing, iron rusting). Lastly discussed concept of Gibbs Free Energy and the equation. |
Comments Entropy is related to microstates. Considers n moles of gas at a given P, V, and T. Macroscopically, nothing is changing. Particulate level: particles can be in different positions and velocities at any given time. Shows 3 possible states of 4 particles (3 microstates). Microstate = microscopic arrangement of all positions and energies of gas particles. Shows the equation that relates entropy to the number of microstates. If W (microstates) increases, S increases. Described as increase in disorder or dispersal of matter or energy. Uses diagrams to explain entropy change in various cases: increasing volume, increasing temperature, gas reactions with changing moles. Excellent explanation of particle speed distribution and entropy. Summarizes: more microstates → positive entropy change. |
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Strengths This video addresses every aspect of Johnstone’s Triangle and makes clear connections between levels. Uses dice probability analogy to explain macro/microstates and incorporates opportunities for self-assessment. Applies science practices (Developing Models, Using Math/Computational Thinking) to explain energy. Strong causal explanation of temperature equilibration with models, numbers, and microstates. Covers entropy topics including 2nd law, microstates, entropy calculations. High multimedia quality: low extraneous load, well-structured, and focused on key concepts for learning. |
Strengths Begins with M&M analogy for mixing, extends to dye in water. Provides particulate models and explains behavior based on microstates and probability, meeting science practice expectations. Explores water freezing with a quantitative entropy calculation and real-world interpretation. Covers core ideas: Change & Stability, Energy, Particulate Nature of Matter. Includes a question prompt for engagement. |
Strengths Effectively connects symbolic and particulate levels using simple diagrams. Gives specific examples with clear representation of entropy changes (e.g., increasing volume, temperature, number of moles, or evaporation). Meets science practice expectations using models and causal reasoning. Emphasizes that increasing disorder = increasing microstates. Clean, focused delivery without distracting effects. |
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Weaknesses Examples of spontaneous processes are given early but not connected to entropy until around the 6-minute mark. Captions are missing for about 2 minutes, disadvantaging some learners. At 13 minutes, it’s a bit long, which may lead to students skipping parts. |
Weaknesses Lower scores on multimedia evaluation for text and coherence. Text stays on screen too long and the constantly shifting background may distract learners. |
Weaknesses Whiteboard-style video sometimes gets visually cluttered due to underlining and circling. Lacks structural organization (e.g., intro, section breaks, summary). Refers to particles as “microscopic” when technically they are sub-microscopic. Minor, but worth refining for scientific accuracy. |