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

7. FixedSlidingRandom

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!  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

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. A measure of molecular vibration in an object. SI Unit: the Kelvin ( K )  Note: not a degree  Absolute Zero = 0 K

28.  Fahrenheit  Celsius  Kelvin Anders Celsius 1701-1744 Lord Kelvin (William Thomson) 1824-1907

29. A beholden vessel never exceeds 212 degrees Fahrenheit. A watched pot never boils!

30. Fahrenheit, Celsius, and Kelvin Temperature Scales.

31. 1 Kelvin = 1 degree Celsius Notice that 1 Kelvin = 1 degree Celsius Boiling point of water Freezing point of water Celsius 100 ˚C 0 ˚C 100˚C Kelvin 373 K 273 K 100 K Fahrenheit 32 ˚F 212 ˚F 180˚F

32. K= o C + 273

33.  Generally require temp’s in Kelvins  T (K) = t (˚C) + 273.15  Body temp = 37 ˚C + 273 = 310 K  Liquid nitrogen = -196 ˚C + 273 = 77 K  Generally require temp’s in Kelvins  T (K) = t (˚C) + 273.15  Body temp = 37 ˚C + 273 = 310 K  Liquid nitrogen = -196 ˚C + 273 = 77 K

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

36. 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

37. The End!!!