2. Not so long ago, in a chemistry lab far far away… May the FORCE/area be with you

4. 1. List 5 properties of gases 2. Identify the various parts of the kinetic molecular theory 3. Define pressure 4. Convert pressure into 3 different units 5. Define temperature 6. Convert a temperature to Kelvin

6.  Airbags fill with N 2 gas in an accident.  Gas is generated by the decomposition of sodium azide, NaN 3.  2 NaN 3 ---> 2 Na + 3 N 2

8.  There is a lot of “free” space in a gas.  Gases can be expanded infinitely.  Gases fill containers uniformly and completely.  Gases diffuse and mix rapidly.

9. To Review  Gases expand to fill their containers  Gases are fluid – they flow  Gases have low density  1/1000 the density of the equivalent liquid or solid  Gases are compressible  Gases effuse and diffuse

13. Gas properties can be modeled using math. This model depends on —  V = volume of the gas (L)  T = temperature (K) › ALL temperatures in the entire unit MUST be in Kelvin!!! No Exceptions!  n = amount (moles)  P = pressure (atmospheres)

14. Ideal Gases Ideal gases are imaginary gases that perfectly fit all of the assumptions of the kinetic molecular theory.  Gases consist of tiny particles that are far apart relative to their size.  Collisions between gas particles and between particles and the walls of the container are elastic collisions  No kinetic energy is lost in elastic collisions

15. Ideal Gases Ideal Gases (continued)  Gas particles are in constant, rapid motion. They therefore possess kinetic energy, the energy of motion  There are no forces of attraction between gas particles  The average kinetic energy of gas particles depends on temperature, not on the identity of the particle.

16. RULE 2 The world won't care about your self-esteem. The world will expect you to accomplish something BEFORE you feel good about yourself.

17. Pressure  Is caused by the collisions of molecules with the walls of a container  Is equal to force/unit area  SI units = Newton/meter 2 = 1 Pascal (Pa)  1 atmosphere = 101,325 Pa  1 atmosphere = 1 atm = 760 mm Hg = 760 torr  1 atm = 29.92 in Hg = 14.7 psi = 0.987 bar = 10 m column of water.

18. Measuring Pressure The first device for measuring atmospheric pressure was developed by Evangelista Torricelli during the 17 th century. The device was called a “barometer” Baro = weight Meter = measure

19. An Early Barometer The normal pressure due to the atmosphere at sea level can support a column of mercury that is 760 mm high.

20. Column height measures Pressure of atmosphere 1111 standard atmosphere (atm) * = 760 mm Hg (or torr) * = 29.92 inches Hg * = 14.7 pounds/in2 (psi) = 101.325 kPa (SI unit is PASCAL) = about 34 feet of water!

21. OK, so it’s really not THIS kind of STP… STP in chemistry stands for Standard Temperature and Pressure Standard Pressure = 1 atm (or an equivalent) Standard Temperature = 0 deg C (273 K) STP allows us to compare amounts of gases between different pressures and temperatures

22. Let’s Review: Standard Temperature and Pressure “STP” P = 1 atmosphere, 760 torr T =  C, 273 Kelvins The molar volume of an ideal gas is 22.42 liters at STP

23. Hint #1. When you don't know what you are doing, do it neatly.

24. A. What is 475 mm Hg expressed in atm? B. The pressure of a tire is measured as 29.4 psi. What is this pressure in mm Hg? = 1.52 x 10 3 mm Hg = 0.625 atm 475 mm Hg x 29.4 psi x 1 atm 760 mm Hg 14.7 psi

25. 101.325 kPa 14.7 psi A. What is 2.00 atm expressed in torr? B. The pressure of a tire is measured as 32.0 psi. What is this pressure in kPa? = 1520 torr 2.00 atm x 760 torr 1 atm = 221 kPa 32.0 psi x

26. Converting Celsius to Kelvin Gas law problems involving temperature require that the temperature be in KELVINS! Kelvins =  C + 273 °C = Kelvins - 273

27. 1. List 5 properties of gases 2. Identify the various parts of the kinetic molecular theory 3. Define pressure 4. Convert any kind of pressure to atmospheres 5. Define temperature 6. Convert a temperature to Kelvin

28. Pass the Clicker!!!

29. 1. 2.533 2. 25.33 3. 142.5 4. 1425 5. Not listed

30. 1. 310 2. 3100 3. 240 4. 2400 5. Not listed

31. 1. -130 2. 533 3. 0.95 4. -13 5. Not listed

32. The End!!!