Spatial Equilibrium: Modeling a Gas

Interactive, scaffolded model

Overview and Learning Objectives

Students observe a model of a gas and are challenged to prevent spatial equilibrium while the model is running. Students learn how spatial equilibrium is determined.

Students will be able to:

• demonstrate, using a computer model, that all initial states result in a similar equilibrium distribution of spatial locations of atoms;
• describe that a gas in spatial equilibrium is a point where the average number of particles is the same in any region.

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Classroom Practice

Nature loves equilibrium. All natural systems tend to move in this direction be it energy minimization, pressure, or osmosis. Spatial equilibrium explores the nature of how molecules move from an area of high concentration to lower concentration. Students set up various starting conditions and watch as the system naturally reaches a spatial equilibrium in which the concentration is, on average, over time, the same everywhere.

This activity is linked closely with two other activities:

Brownian Motion: http://molo.concord.org/database/activities/40.html

Diffusion, Osmosis, and Dialysis: http://molo.concord.org/database/activities/223.html

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Central Concepts

Key Concept:

Continual movement of atoms results in motion that appears random and causes particles to be distributed evenly among the atoms in a gas.

Additional Related Concepts

Systems

• Equilibrium

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Textbook References

• Biology: Concepts and Connections (Pearson) 5th Edition - Chapter 22: Respiration: The Exchange of Gases
• Biology: Exploring Life - Chapter 30: The Circulatory and Respiratory Systems
• Biology: The Dynamics of Life - Chapter 8: Cellular Transport and the Cell Cycle

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Benchmarks and Standards

NSES

• Physical-Science: Energy Conservation / Entropy - 4 Everything tends to become less organized and less orderly over time (Full Text of Standard)
  
  

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Extensions and Connections

You might find useful the classroom support available at: http://www.concord.org/~barbara/workbench_web/unit1/index.html

in particular

http://www.concord.org/~barbara/workbench_web/unit1/1-07ModelingAGas.html

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Additional Info

Additional Questions

Imagine that you are at a party where someone dared you to pop one of the Helium balloons in a room that has all the windows and doors closed. Describe what would happen to those Helium atoms once they have been released from the balloon. Specifically, talk about their eventual position inside the room and how they arrived there.

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Activity Credits

Created by CC Project: Molecular Workbench using Molecular Workbench + Pedagogica

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Requirements

• Java 1.4+ - Java 1.4+ is available for Windows, Linux, and Mac OS X 10.3 and greater.

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Technical Notes

Does not work on all Macs.

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