1. LECTURE 5.1 – GASES, PRESSURE, AND DIFFUSION

2. Today’s Learning Targets
LT 5.1 – I can explain how pressure is created through the collisions of molecules with a surface.
LT 5.2 – I can discuss how the diffusion of a gas through a space is the result of the random motion of a gas molecule

3. What are gases?

4. I. Gases One of three states of matter.
Move in constant random motion.
They fill an entire container and are spread very far apart.

5. What Gases Look Like at Atomic Level

6. What is pressure?

7. I. Pressure
The collisions of gas molecules with a surface are what creates pressure.
Pressure the amount of force that is exerted per unit of area.

9. II. Pressure Has Many Units
Pressure is measured with a barometer and it is measured in numerous units.
The units of pressure are atm, bar, mm Hg, Pa, and torr.

10. What is diffusion?

11. I. Diffusion
Diffusion is the movement of particles from regions of higher density to regions of lower density.
Because gases are constantly in random motion, they spread out from one another quickly.
This random motion of gases is what explains the process of diffusion
Ask students the following questions: Why don’t you smell gases instantaneously if gases are moving so quickly? If you have a gas that is 2 g/mol and one that is 52 g/mol, which do you think you would smell first?

13. You’ve Seen Diffusion Before!