Benchmarks 2061 for Grades 6-8

The Physical Setting

4d Structure of matter:

• Atoms and molecules are perpetually in motion. Increased temperature means greater average energy of motion.

The Mathematical World

9b Symbolic Relationship:

• Mathematical statements can be used to describe how one quantity changes when another changes. Rates of change can be computed from differences in magnitudes and and vice versa.

• Graphs can show a variety of possible relationships between two variables. As one variable increases uniformly, the other may do one of the following: increase or decrease steadily, increase or decrease faster and faster, get closer and closer to some limiting value, reach some intermediate maximum or minimum, alternately increase and decrease indefinitely, increase or decrease in steps, or do something different from any of these.

9c Shapes:

• The graphic display of numbers may help to show patterns such as trends, varying rates of change, gaps or clusters. Such patterns sometimes can be used to makepredictions about phenomena being graphed.

Habits of Mind

12d Communication Skills:

• Organize information in simple tables and graphs and identify relationships they reveal.

National Science Education Standards grades 5-8

A Scientific Inquiry

• Use appropriate tools and techniques to gather, analyze, and interpret data. Use mathematics in all aspects of science inquiry. Develop descriptions, explanations, predictions, and models using evidence.

National Science Education Standards grades 9-12

B Physical Science

• Conservation of energy and the increase in disorder Structure and properties of matter

Intended Learning Outcomes:

• 1a. Make observations and measurements (using instruments as appropriate).
• 2a. Identify variables and describe relationships between them.
• 2d. Collect and record data using procedures designed to minimize error.
• 2e. Analyze data and draw warranted inferences.

We are constantly being exposed to the behavior of gases. Each time we pump up a tire, blow up a balloon, use a spray can, or experience the cooling of gases as they escape from a gas storage container, we are reminded of how gases behave with changes in temperature, volume, pressure, or number of particles. In an astronomical scale, we know that star formation involves contraction of gas clouds to produce dense, high-pressure cores capable of fusion reactions.

These labs will help your students investigate the behavior of gases due to changes in variables like volume, temperature, and number of particles.

This experience with molecular motion in gases can be extended to help students understand perpetual motion in all states of matter. Students can transfer this relationship to the change in temperature and the corresponding change in vibration of molecules in a solid.

Activity 1 - Gas Particles in Motion: Changing Volume

Students will investigate Boyle's Law, which relates the effect of changes in volume of a confined gas on pressure at constant temperature. Students will use data collected in the lab to discover that there is an inverse relationship between these two variables.

Activity 2 - Gas Particles in Motion: Changing Temperature

Students will investigate Gay-Lussac's Law, which relates how changing the temperature of a gas that is kept at constant volume affects the pressure of the gas. Using their data, students will understand that there is a direct relationship between these variables.

Activity 3 - Gas Particles in Motion: Changing Volume and Temperature

Students will investigate Charles' Law, which relates changes in the temperature of a confined gas kept at a constant pressure to the volume of the gas.

The gaseous state of matter consists of particles (gas molecules like oxygen, nitrogen, and carbon dioxide) which, according to the kinetic theory of gases, are in constant motion with enough kinetic energy such that they rarely interact with one another. When gas particles collide with the walls of a container, they rebound with no apparent loss of energy. These characteristics describe an "Ideal Gas." Experimental evidence suggests that many common gases making up air behave in this manner when studied at temperatures well above their boiling points for a given pressure.

The behavior of gases has been scientifically investigated starting with Robert Boyle's work in the 1600s, followed by Jacques Charles' and Joseph Gay-Lussac's work. Together these studies led to the so called "Gas Laws" which relate volume (V), pressure (P), temperature (T) and numbers of particles of gas. Consequently we have the following relationships:

• PxV = a temperature dependent constant - Boyle's Law
• P/T = volume dependent constant - Gay-Lussac's Law
• V/T = a pressure dependent constant - Charles' Law
• P is proportional to the mass of particles times their average velocity times frequency of collision of particles with the walls of the container divided by the area of the container's walls.

Technical consultation and assistance is freely available to teachers and schools interested in using the ASPIRE website, on-line labs, and curriculum materials. In time resources will be made available to assist schools lacking the computer technology required to access the labs. For technical assistance and resource information please contact the following:

Teacher materials and information:
julie@cosmic.utah.edu