You will put this stuff on a leash and own it like a dog. Gas Class #5 OB: You will become a gas math master You will put this stuff on a leash and own it like a dog. What’s your dog’s name?

Avogadro’s Hypothesis This is so important, it’s one slide but it’s epic thinking. You should consider putting this statement (and diagram) in a frame, and hang it in your bathroom, forever. “Equal volumes of DIFFERENT gases, at THE SAME temperature + pressure have the SAME number of moles, and the SAME number of particles”.

“Equal volumes of DIFFERENT gases, at THE SAME temperature + pressure Have the SAME number of moles, and the SAME number of particles”. NH3 He CO2 J He CO2 NH3 Volume 22.4 L Temp. 273 K Pressure 101.3 kPa Particles 6.02 x 1023 moles 1.0 mole

Volume as a function of Temperature. Pressure as a function of Volume. Draw these three graphs, casually, but correctly. Use P, V, and T for axis labels. Draw proper lines. Indicate if each graph is directly or inversely proportional. Volume as a function of Temperature. Pressure as a function of Volume. Pressure as a function of Temperature.

Draw these three graphs, casually, but correctly Draw these three graphs, casually, but correctly. Use P, V, and T for axis labels. Draw proper lines. Indicate if each graph is directly or inversely proportional. Volume as a function of Temperature. Pressure as a function of Volume. Pressure as a function of Temperature. V P P T V T DIRECTLY Proportional INVERSELY Proportional DIRECTLY Proportional This one is hard to draw, but it’s a smooth curve-alicious curve

Convert 145.6 kPa into atmospheres

Convert 145.6 kPa into atmospheres X 1.0 atm 101.3 kPa = 1.437 atm (4SF)

Convert 1.06 atm into millimeters of mercury Change 844 mm of Hg into kilopascals

X = 806 mm Hg (3SF) X = 112 kPa (3SF) 1.06 atm 1 760 mm Hg 1.0 atm Convert 1.06 atm into millimeters of mercury Change 844 mm of Hg into kilopascals 1.06 atm 1 X 760 mm Hg 1.0 atm = 806 mm Hg (3SF) 844 mm Hg 1 X 101.3 kPa 760 mm Hg = 112 kPa (3SF)

Ideal Gases vs. Real Gases Ideal gases do not exist, except as the idea of “perfect” gases. Real gases are real, they are the ones you know, like N2, CO2, O2, NH3, Ne, etc. Most real gases remain gases because of the kinetic molecular theory of gases (and the Sun’s free energy each day). Ideal gases can’t become liquids, no matter the temperature or pressure, since they’re FAKE. Real gases can become liquid or solid. Real gases act most ideally under these 2 conditions: High temperature and low pressure. Because with high temperature, they bang around so hard, they are less likely to stick together. With low pressure, they are not as likely to even bump into each other, which makes it hard to form into a liquid.

Ideal Gases vs. Real Gases When comparing different real gases, at the same temperature and pressure, the gas with the smallest particles, are the most ideal. If you had 2.45 liters of neon, of carbon dioxide, and of propane, all at STP, which would act MOST IDEAL? Neon = single atoms = MOST IDEAL Carbon dioxide = 3 atom molecules Propane (C3H8) = 11 atom molecules = LEAST IDEAL

NOW: 54 gas problems, numbers: 22 – 33 Answers to be handed out at the end of class today. Check over your work. Next, last demo diagram: Pressure + Temperature

Heat up some water in a can with a hot plate Demo Diagram #3 The Can Crush Pressure is directly proportional to Temperature Water in can converts to steam with q = mHV Steam pushes up, pushing air out of the can. The can fills with H2O gas, at normal pressure (top is open) Heat up some water in a can with a hot plate

Temperature + pressure are directly proportional As the temperature of the steam (gas) in the can drops upon cooling (it condenses to liquid) The pressure decreases also. Temperature + pressure are directly proportional

Temperature + pressure are directly proportional. The gas cools down (all the way to a liquid). As the temperature drops, the pressure decreases as well. Reverse: as the temperature is increased, the pressure boosts up too. (more KE = more Collisions) Temperature as function of Pressure T Pressure Temperature + pressure are directly proportional.