1. Important Concepts: 1. Kinetic Theory 2. Ideal Gas 3. Gas Pressure 4. STP Kinetic Theory

2. Gases are composed of small, separate particles called molecules. Gas molecules are in constant motion. All collisions between particles are perfectly elastic.

3. Kinetic Theory The molecules of a gas display no attraction or repulsion for one another. The average kinetic energy of the molecules is directly proportional to the Kelvin temperature of the gases

4. Ideal Gas Gas whose behavior conforms to the kinetic theory It is theoretical Extremely high pressure and low temperatures cause gas particles to deviate from ideal behavior What does it mean by conforms to the kinetic theory? Gases are composed of small, separate particles called molecules. Gas molecules are in constant motion. All collisions between particles are perfectly elastic. The molecules of a gas display no attraction or repulsion for one another. The average kinetic energy of the molecules is directly proportional to the Kelvin temperature of the gases

5. Gas Pressure Pressure = force/area What does this actually mean to you? Look at the two shoes to the left. Which would you rather have step on your toe? Why?

6. Gas Pressure Atmospheric Pressure- The pressure the earth’s atmosphere exerts due to its weight Why don’t we “feel” this pressure? Because this pressure is what our bodies are used to AND there is equal and opposite pressure inside us causing us to be at equilibrium with our environment

7. Atmospheric Pressure What happens to your ear drums are you drive up a mountain? The pressure decreases so your ear drums need to “pop” Is atmospheric pressure dangerous? Take a look at this demo before answering. http://www.youtube.com/watch?v=JsoE4F2Pb20

8. Crush the Can!!!

9. Barometer Instrument used to measure atmospheric pressure Invented by Torricelli

10. Normal Atmospheric Pressure Also called standard pressure 760 mm Hg 760 torr 1 atm (atmosphere) 101.3 kPa These are all equivalent values. What does this mean? Conversion between pressure units! Convert 600. torr to kPa 79.97  80.0 kPa Convert 2.1 atm to mm Hg 1596  1600 mm Hg

11. STP: Standard Temperature and Pressure: 1 atm 0 o C Why do we have a standard for temperature and pressure? Allows for scientists to communicate the conditions they run experiments under Allows for a uniform approach to studying gases Gives you the students a starting point when considering gas laws

12. What is Gas Pressure Really? Why do gases have pressure? (think in terms of the Kinetic Theory) The gas molecules hit the sides of the container. The number of times it hits the sides correlated to the pressure of the of the chamber. What happens to the pressure when you change the temperature? If you increase the temperature, the molecules go faster and hit the walls more thus increasing temperature. If you decrease the temperature, the molecules go slower and hit the walls less often thus decreasing the pressure.

13. Decreasing Volume How do the collisions with the wall change? Increase collisions How does the space between molecules change? Decrease distance between molecules How do you think this effects pressure? Increases Pressure

14. Manometer Instrument used to measure gas pressure U-shaped tube partially filled with mercury One end open to confined gas One end open to atmosphere ρ (rho) = density g = gravity (9.8 m/s) h = difference in height

15. Quiz

16. Question 1 What does STP stand for AND what are the values associated with it? A. Saturated temperature point AND 0 0 C at 1 atm B. Standard temperature and pressure AND 0 0 C at 1 atm C. Standing Tempo Pianissimo and 100 0 C at 0 atm D. Standard temperature and pressure AND 100 0 C at 0 atm

17. Question 2 What causes gases to not behave ideally? A. High Pressure B. Bad upbringing C. Being too hot D. Low temperature E. Low pressure F. Improper measuring

18. Question 3 What happens to the molecules of gas if the temperature is increased AND what happens to the pressure? A. The molecules slow down B. The molecules stick together C. The molecules speed up D. The pressure decreases E. The pressure increases F. The pressure stays the same

19. Question 4 What is the direct measure of average kinetic energy? A. Density B. Pressure C. Volume D. Temperature E. Conductivity

20. Question 5 What is an ideal gas? A. A gas that interacts with its neighbor gas particles, can stop, and stick together B. A gas that elastically bounces, has no constant motion, no attraction C. A gas that elastically bounces but stops from time to time D. A unstoppable particle that cannot be contained except by the incredible hulk