Lesson 12.1 Gases
Density density pepsi vs diet pepsi 3.5 mindensity pepsi vs diet pepsi 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 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 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 P total = P 1 + P 2 + P P n O 2 + CO 2 + N 2 P CO 2 = 0.70 P N 2 = 0.12 P total = 0.97 atm Find P O 2 = 0.97 – 0.70 – 0.12 = 0.15 atm
Textbook page 409 # 4,5,6
p. 409 # 4,5,6 4.P H2 = 161 mmHg 5.P total = kPa 6.P CO2 = 10.2 kPa
Explain how a person can break a board, like in Karate?