Gases and Their Properties CH 11

Areas to Explore  Gas Particles and Motion Gas Particles and Motion  Gas Variables Gas Variables  Manipulating Variables  Pressure and Volume Pressure and Volume  Pressure and Temperature Pressure and Temperature  Volume and Temperature Volume and Temperature  Volume and Amount Volume and Amount  Combining Gases Combining Gases

Kinetic Theory – all matter is in motion The energy of moving objects (even electrons, atoms, molecules) is called Kinetic Energy. Kinetic Molecular Theory Top

 Gases:  Have mass.  Are compressible.  fill their containers  Diffuse Gases can move through each other rapidly.  exert pressure  Pressure is dependent on Temp.

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Gas Variables Pressure Temperature volume

Pressure Pressure is force per unit area Atmospheric pressure, or air pressure – (mixture of gases) caused by gases in atmosphere colliding with each other. Air pressure lower at higher altitudes. Greatest at sea level. External Pressure vs. Internal pressure

Which shoes create the most pressure? Top

Temperature A measure of the average kinetic energy of the particles in a sample of matter Does this mean it always relates to HEAT? What happens when molecules STOP moving?

Temperature  Always use absolute temperature (Kelvin) when working with gases. ºF ºC K K = ºC Top

Volume the space that a substance or shape occupies or contains. How do gases ‘have’ volume? Standard unit: L or mL Top

Pressure and Volume P V PV = k As Pressure of the surroundings is increased, FORCE on the system is increased. This will push the molecules closer together, decreasing volume As P increased, V decreased INVERSLY RELATED Top

V T Volume and Temperature At Constant pressure temperature increased makes the molecules move faster This will make them increase the space they occupy! As T increases, V increases DIRECTLY RELATED : V 1 T 2 = V 2 T 1 Top

P T Pressure and Temperature At Constant Volume temperature increased makes the molecules move faster This will make them increase the force they exert! As T increases, P increases DIRECTLY RELATED Top

V n Volume and amount of Gas At constant pressure and temperature, as the amount of gas is increased, the space it takes up will increase! Directly Related Top

Can we combine all the equations into ONE formula? Top

Combining Gases The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases. P total = P 1 + P Top