Episode I ATTACK OF THE GAS

2. Not so long ago, in a chemistry lab far far away… May the FORCE/area be with you Episode I ATTACK OF THE GAS Gas, being of upmost importance to the entire galaxy and your life, is in constant battle due to the ruthless variations of temperature, pressure, and the amount of particles. It is imperative that you understand properties of gases and how those ruthless variations affect the gases. You will need to make some minor assumptions to conquer this topic. However, there is certainty that you will prevail…

4. Gas Laws: IntroductionAt the conclusion of our time together, you should be able to: List 5 properties of gases Identify the various parts of the kinetic molecular theory Define pressure Convert pressure into 3 different units Define temperature Convert a temperature to Kelvin

5. Red-Neck Innovations:

6. Importance of Gases • Airbags fill with N2 gas in an accident. • Gas is generated by the decomposition of sodium azide, NaN3. • 2 NaN3 ---> 2 Na + 3 N2

7. THREE STATES OF MATTER Fixed Sliding Random

8. General Properties of Gases • 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

10. Most Caring Person!! An eye witness account from New York City on a cold day in December. Some years ago a little boy, about 10-years-old, was standing before a shoe store on the roadway, barefooted, peering through the window, and shivering with cold. A lady approached the young boy and said, "My, but you're in such deep thought staring in that window!“ "I was asking God to give me a pair of shoes,“ was the boy's reply.

11. Most Caring Person!! The lady took him by the hand, went into the store, and asked the clerk to get half a dozen pairs of socks for the boy. She then asked if he could give her a basin of water and a towel. He quickly brought them to her. She took the little fellow to the back part of the store and, removing her gloves, knelt down, washed his little feet, and dried them with the towel. By this time, the clerk had returned with the socks. Placing a pair upon the boy's feet, she purchased him a pair of shoes.

12. Most Caring Person!! She tied up the remaining pairs of socks and gave them to him. She patted him on the head and said, "No doubt, you will be more comfortable now.“ As she turned to go, the astonished kid caught her by the hand, and looking up into her face, and with tears in his eyes, asked her. "Are you God's wife?"

13. Properties of Gases 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 (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. Bill Gates' RulesHere is a list of 11 things that many high school and college graduates did not learn in school. In his book, Bill Gates talks about how feel-good, politically-correct teachings created a full generation of kids with no concept of reality and how this concept has set them up for failure in the real world. 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/meter2 = 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 17th 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. Pressure Column height measures Pressure of atmosphere • 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. And now, we pause for this commercial message from STP 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 = 0°C, 273 Kelvins

23. 15 Helpful Hints On The Lab Report from Mr. T’s Vast Lab Experience!!! Hint #1. When you don't know what you are doing, do it neatly. 

24. Pressure Conversions 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 atm 760 mm Hg 475 mm Hg x = 0.625 atm 760 mm Hg 14.7 psi 29.4 psi x = 1.52 x 103 mm Hg

25. Pressure Conversions – Your Turn 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? 760 torr 1 atm 2.00 atm x = 1520 torr 101.325 kPa 14.7 psi 32.0 psi x = 221 kPa

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

27. Converting Temperature

28. 3 Temperature Scales Fahrenheit Celsius Kelvin Anders Celsius 1701-1744 Lord Kelvin (William Thomson) 1824-1907

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

30. Fahrenheit, Celsius, and Kelvin Temperature Scales.

31. 3 Temperature Scales 212 ˚F 100 ˚C 373 K 100 K 180˚F 100˚C 32 ˚F 0 ˚C 273 K Fahrenheit Celsius Kelvin Boiling point of water Freezing point of water Notice that 1 Kelvin = 1 degree Celsius

32. Celsius and Kelvin K= oC + 273

33. Calculations Using Temperature 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

34. Calvin’s Thoughts on Lunch:

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. Gas Laws: IntroductionLet’s see if you can: List 5 properties of gases Identify the various parts of the kinetic molecular theory Define pressure Convert any kind of pressure to atmospheres Define temperature Convert a temperature to Kelvin

37. The End!!!