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Beginner's Guide to Rockets
Gas Density

Subject Area: Chemistry
Grade Level: 9-12
Time Required: 3 class periods
National Standards:


  • Unifying Concepts and Processes:
    • Change, constancy, and measurement
    • Form and function.
  • Science as Inquiry:
    • Understandings about scientific inquiry.
    • Abilities necessary to do scientific inquiry
  • Physical Science: Structure and properties of matter.


  • Research Tools - Use content-specific tools, software and simulations (e.g., environmental probes, graphing calculators, exploratory environments, Web tools) to support learning and research.
  • Problem-Solving and Decision-Making Tools - Routinely and efficiently use on-line information resources to meet needs for collaboration, research, publications, communications, and productivity.


You and your group will design your own procedure to calculate the mass of the gas molecules in the classroom by measuring the volume of the classroom and researching the density of air. You and your group will then apply the changes in air density with altitude and the effects on rocket engine performance.

RocketThrust, which was created at NASA Glenn Research Center to illustrate an example of their research, simulates the aero-thermodynamics of a rocket engine nozzle. With this software you can change many of the variables in a rocket engine to study how they work. You can change the fuels, operating conditions, and even design your own nozzle. RocketThrust is intended for science and math students from secondary schools through undergraduate engineering.

The Beginner's Guide to Rockets is a Web site of information prepared by the NASA Glenn Research Center to help you better understand rockets and rocket engine propulsion. Click on the Beginner's Guide Index to access the list of slides. Open the slides entitled Air Properties Definitions and/or Gas Density. Read the descriptions as background information to help you complete the activity.


A. Because the target group is a Chemistry class, the lesson is presented with a rather open procedure by design. Students are not told step by step exactly what to do. They are given the objectives and in small groups are to decide what materials, information, and procedures are required to determine the mass of the gas molecules in the room.

B. This lesson also helps students to realize that air has mass. Once students have determined the mass of the molecules in the room they can then analyze how the properties of those molecules will change with altitude in our atmosphere and how that applies to the functioning of a rocket engine. Another piece of software, called AtmosModeler, can also be used in this exercise. This software includes a mathematical model of the standard day atmosphere which is used by aeropsace engineers.

C. A suggested option is to have the students predict the mass of the gas molecules in the classroom before they begin their procedure. This may help remove some misconceptions about gases.


You and your group will be assessed on your description of your procedure, the presentation of your data and calculations, and the final results for both the mass of gas molecules in the classroom and the functioning of a rocket engine.


Reports should be neat, in chronological order, and include measurements with units. All sections should be clearly identified.

Submitted by: Norma Holowach, Lakeview High School, Cortland, Ohio

Related Sites:
Rocket Index
Rocket Home
Exploration Systems Mission Directorate Home


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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Jun 12 2014

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