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Episode I ATTACK OF THE GAS

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.

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Episode I ATTACK OF THE GAS

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  1. 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…

  2. Gas Laws: Avogadro’s and IdealAt the conclusion of our time together, you should be able to: Describe Avogadro’s Law with a formula. Use Avogadro’s Law to determine either moles or volume Describe the Ideal Gas Law with a formula. Use the Ideal Gas Law to determine either moles, pressure, temperature or volume Explain the Kinetic Molecular Theory

  3. Kid’s Letters to God:

  4. twice as many molecules Avogadro’s Law Equal volumes of gases at the same T and P have the same number of molecules. V = an V and n are directly related.

  5. Avogadro’s Law Summary • For a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas (at low pressures). • V=an • a = proportionality constant • V = volume of the gas • n = number of moles of gas

  6. Standard Molar Volume Equal volumes of all gases at the same temperature and pressure contain the same number of molecules. - Amedeo Avogadro

  7. Avogadro’s Law Practice, Page 31:1 V1 V2 n1 n2 4.00 L 7.12 L 0.21 mol n2 0.37 mol total 0.16 mol added

  8. Hittite Innovations:

  9. IDEAL GAS LAW P V = n R T Brings together gas properties. Can be derived from experiment and theory. BE SURE YOU KNOW THIS EQUATION!

  10. Ideal Gas Law • PV = nRT • P = pressure in atm • V = volume in liters • n = moles • R = proportionality constant • = 0.08206 L atm/ mol·K • T = temperature in Kelvins Holds closely at P < 1 atm

  11. No Comment Needed…

  12. Review of Kinetic Molecular Theory • Particles of matter are ALWAYS in motion • Volume of individual particles is  zero. • Collisions of particles with container walls cause pressure exerted by gas. • Particles exert no forces on each other. • Average kinetic energy µ Kelvin temperature of a gas.

  13. Deviations from Ideal Gas Law • Real molecules have volume. The ideal gas consumes the entire amount of available volume. It does not account for the volume of the molecules themselves. • There areintermolecular forces. An ideal gas assumes there are no attractions between molecules. Attractions slow down the molecules and reduce the amount of collisions. • Otherwise a gas could not condense to become a liquid.

  14. R is a constant, called the Ideal Gas Constant Instead of learning a different value for R for all the possible unit combinations, we can just memorize one value and convert the units to match R. R = 0.08206 L • atm mol • K

  15. Using PV = nRT How much N2 is required to fill a small room with a volume of 960 cubic feet (27,000 L) to 745 mm Hg at 25 oC? Solution 1. Get all data into proper units V = 27,000 L T = 25 oC + 273 = 298 K P = 745 mm Hg (1 atm/760 mm Hg) = 0.98 atm And we always know R, 0.08206 L atm / mol K

  16. Using PV = nRT How much N2 is required to fill a small room with a volume of 960 cubic feet (27,000 L) to P = 745 mm Hg at 25 oC? Solution 2. Now plug in those values and solve for the unknown. PV = nRT RT RT n = 1.1 x 103 mol (or about 30 kg of gas)

  17. Is It REALLY Worth Fighting Over???

  18. University of Washington Chemistry Midterm Exam Question Is Hell exothermic or endothermic? Support your answer using the Ideal Gas Law. PV=nRT (P)ressure x (V)olume = number of particles of the gas (n) x the gas constant (R) x the (T)emperature of the gas One enterprising student wrote the following:

  19. First we need to know how the number of particles (souls) are changing over time. Are the number of souls increasing or decreasing? What is the rate of souls entering Hell as compared to souls leaving Hell? Most religions teach that once in Hell, always in Hell, so lets assume that no soul is leaving Hell. Most religions also teach that if you do not abide by their religious teachings, you will go to Hell. So let’s assume that most souls are going to Hell.

  20. Given the current birth and death rates, we can assume that the number of particles (souls) in Hell is increasing exponentially. According to the Ideal Gas Law, if n, the number of particles (souls) is increasing exponentially, for the temperature and pressure to stay the same, the volume must increase. There are therefore two possibilities:

  21. 1. If the volume of Hell is not expanding or expanding slower than the increase in particles (souls), then the temperature and pressure in Hell will increase until all Hell breaks loose. (Exothermic) 2. If the volume of Hell is expanding faster than the increase of particles (souls), then the temperature and pressure will drop until Hell freezes over. (Endothermic)

  22. If we accept the postulate given to me by Ms. Krissy Jones during my freshman year that “it will be a cold day in Hell before I sleep with you,” and taking into account that I still have not succeeded in having sexual relations with her, than the second (2) possibility cannot be true. • Therefore, I am sure that Hell is exothermic!

  23. University of Washington Chemistry Midterm Exam Question Is Hell exothermic or endothermic? Support your answer using the Ideal Gas Law. PV=nRT The kid got an “A”!!!!!!!!!!!!!!!!!

  24. Ideal Gas Law Problems, Page 32:1 Using PV = nRT (5.6 atm) (12 L) (4.0 mol) (0.08206 atm*L/mol*K) (T) 2.0 x 102 K

  25. Gas Laws: Avogadro’s and IdealLet’s see if you can: Describe Avogadro’s Law with a formula. Use Avogadro’s Law to determine either moles or volume Describe the Ideal Gas Law with a formula. Use the Ideal Gas Law to determine either moles, pressure, temperature or volume Explain the Kinetic Molecular Theory

  26. Review of Kinetic Molecular Theory • Particles of matter are ALWAYS in motion • Volume of individual particles is  zero. • Collisions of particles with container walls cause pressure exerted by gas. • Particles exert no forces on each other. • Average kinetic energy µCelcius temperature of a gas.

  27. Try this One!!

  28. A sample of argon gas is at a pressure of 148 kPa and temperature of 27.0oC in a rigid 42.0 L tank. How many moles of argon does this tank contain? (1 atm = 101.325 kPa) • 252 mol • 2.49 mol • 27.7 mol • 2.80 x 103 mol • Not listed

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