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• Количество слайдов: 20 Lesson 12. 1 Gases Density • density pepsi vs diet pepsi 3. 5 min • volume of a marble • density animation What are the main physical properties of gases? • Gases assume the volume and shape of the container. • Gases are most compressible of states of matter. • Gases will mix evenly and completely when confined to same container. • Gases have much lower densities than liquids and solids. List the Gases Periodic Table in back of textbook Why diatomic? Noble Gases • Single atoms • Complete outer valance shell • Octet rule is satisfied Kinetic Molecular Theory • Gases have similar physical properties • Little variation in behavior • Kinetic = Greek word “to move” Particles in motion • Particles are small – Lots of empty space – No significant attraction or repulsion forces • Constant random motion Kinetic Energy = ½ mv 2 • Molecules travel in a straight line • Hit a wall or another molecule then Energy is transferred – no energy is lost • m is mass • v is velocity (speed and direction) Compression and Expansion Diffusion and Effusion • Diffusion – smell cooking throughout the house • Effusion – gas escapes from a small hole different rates depends on size • Smaller particles travel faster Diffusion Ratio NH 3 or HCl Back to molar mass! NH 3 36. 5 g/mol and HCl 17. 0 g/mol Find Diffusion Ratio N 2 and Ne CO and CO 2 Pressure Think about it Walk on deep snow with boots, snow shoes, skis. Which sink the most? Why? Pressure = force / unit of area The pressure in car or bicycle tires is measured in pounds per square inches. Car tires 26 -30 lb/sq. in. Bicycle tires 40 -60/sq. in. Who will wear out the carpet first? 125 lbs woman wearing high heels? Or, same woman wearing flats? Why? Barometer or Manometer • Instruments that measure pressure Units of Measure Dalton’s Law Partial Pressure Ptotal = P 1 + P 2 + P 3 +. . . + Pn O 2 + CO 2 + N 2 PCO 2 = 0. 70 PN 2 = 0. 12 Ptotal = 0. 97 atm Find PO 2 = 0. 97 – 0. 70 – 0. 12 = 0. 15 atm Textbook page 409 # 4, 5, 6 p. 409 # 4, 5, 6 4. PH 2 = 161 mm. Hg 5. Ptotal = 13. 78 k. Pa 6. PCO 2 = 10. 2 k. Pa Explain how a person can break a board, like in Karate? 