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Properties of Gases: A Case Study of the Bends


Eric J. Herrera
Department of Chemistry
California State University, Sacramento


In 2012, Mike Prickett, a world-renowned underwater cinematographer, was working on a commercial photo shoot in Tahiti when he witnessed a fellow diver sinking and drowning. While saving the drowning victim, Mike fell victim to decompression sickness (the bends), which led to paralysis from the chest down. This interrupted case study uses Mike's story to explore the kinetic molecular theory of gases, gas laws (specifically Boyle's Law and Henry's Law), hyperbaric oxygen therapy, and partial pressures of gases in mixtures, including the human blood stream. Students investigate how SCUBA equipment works and use a sketching activity to visualize the pressure changes that affect divers as they travel underwater. In-class demonstrations are used to help students visualize the types of conditions that effect changes in gas behavior and to draw connections between them, theoretically and in real life. The case was originally designed for use in a lab setting for undergraduate introductory chemistry or General Organic and Biochemistry (GOB) course, or for an introductory level chemistry class for nursing students.

  • Identify the types and amounts of each gas in the atmosphere.
  • Use the behavior of gas mixtures to calculate the amount of gas dissolved in a solution.
  • Use conversion factors to calculate pressure in a variety of measurement units.
  • Understand how hyperbaric oxygen therapy (HBOT) works and what conditions it is prescribed for.
  • Use the kinetic molecular view of gases to explain their behavior at different temperatures and pressures.
  • Explain how intermolecular forces change as gas temperature changes.
  • Apply the individual and/or combined gas laws to gas samples under various conditions.
Keywords: Gas laws; Boyle’s law; Henry’s law; kinetic molecular theory; the bends; decompression sickness; hyperbaric oxygen therapy; HBOT; blood gases; gas pressures; dissolved gases; conversion factors; gas solubility; paralysis; diving; SCUBA; Tahiti
Topical Area: N/A
Educational Level: High school, Undergraduate lower division
Formats: PDF
Type/Method: Directed, Discussion, Interrupted, Laboratory
Language: English
Subject Headings: Chemistry (General)   Biochemistry   Organic Chemistry   Physiology   Sports Science   Nursing  
Date Posted: 12/5/2014
Date Modified:
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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