Understanding Air Particles in Foam Cubes and Syringes

1. Air As Particles Lecture • FOSS Kit Chemical Interactions • Investigation 3

2. Air in Syringe

3. Foam Cube Summary

4. Foam Cube Summary • The density of the air particles in each foam cube is about even before the surrounding air is compressed. • The cells in the closed-cell foam are all isolated and sealed. • Examples: Bubble Wrap and • Blue Foam Cube

5. Closed Cell Cube

6. Foam Cube Summary • The cells in the open-cell foam are all connected to one another. • The cube is a mass of channels and pathways that connect throughout the cube. • Air particles can pass easily through the • connected cells. • Example: Grey Foam Cube

7. Open Cell Cube

8. Closed Cell Cube (After Pressure)

9. Closed Cell Cube (After Pressure) • The air inside the cells of the closed-cell foam gets compressed. • The cells get smaller. • Smaller cells makes the whole cube get smaller.

10. Closed Cell Cube (After Pressure) • The particles get closer together and the cells get smaller, but each cell has the same number of particles inside.

11. Open Cell Cube (After Pressure)

12. Open Cell Cube (After Pressure) • The air inside the open-cell foam is compressed when the surrounding air is compressed. • The size of the cells doesn’t change, but the number of particles crowded into the cells increases.

13. Comparing Foam Cubes

14. Distance Between Particles • The distance between the air particles is the same in the open-cell and closed-cell foam before the pressure.

15. Distance Between Particles • Distance between the air particles is the same in the open-cell and closed-cell foam after pressure. • There are, however, twice as many particles in the cells in the open-cell cube.

16. Gas in Syringe • Foss Web Multimedia: Gas In Syringe • http://www.fossweb.com/

17. Information on Gas (As Matter and Particles) • Gases are composed of individual particles. • The particles are not connected to one another. • Move through space freely. • Travel in straight lines until they run into something. • Collision of gas particles (i.e. in a syringe) bounce off and keep going in a different direction still in a strait line.

18. Air as Mixture • Air is the name of the mixture of gases that form Earth’s atmosphere. • Composed mostly of nitrogen (N2) • Nitrogen is gas particle N2 • Also in air is Oxygen (O2) particles, a few Argon (Ar) particles, and a few Carbon Dioxide (CO2) and water (H20) particles.

19. Gas Particles • Very, very small in size. • Cubic centimeter of air (like the cubes) contains 27 quintillion particles • 27,000,000,000,000,000,000

20. Air Particles • Every air particle crashes into another air particles (or some other object) 10 billion times per second! • Particles of gas are far apart. • Compare to a basketball in a room: • Space between is 2.3 m (7.5’) apart • Move at 300 m/s (670 mph)

21. What is between an air particle? • Nothing! • Void. • There is just space between particles, no matter.

22. Compressed Air • Because gas particles are pretty far apart, with only space between them, they can be forced closer together. • Force on gas (i.e. like pushing down on the plunger of a syringe, the air particles can be pushed closer together. • Compressed air!

23. Why can’t you push the particles until they touch? • The fast-moving particles push back on the syringe plunger with a force when they hit it. • As particles in gas get closer together, they hit the plunger more frequently. • The harder you push, the harder they push. • There is a limit to how close together you can push the air particles.

24. What happens when force is removed from the syringe plunger? • When force applied to the syringe plunger is removed: • the particles inside the syringe push up on the plunger and it moves out of the syringe barrel. • It moves out until the force applied by the air particles pushing the plunger up is equal to the force applied by the air particles outside pushing the plunger down.

25. FOSS Web Multimedia • Periodic Table • Gas in Syringe • http://www.fossweb.com/