Gases and the Kinetic Molecular Theory

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Gases and the Kinetic Molecular Theory
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Speeds of gas molecules. For a single molecule.
Kinetic energy is KE ½ mv2 m mass v
velocity For a collection of gas molecules,
the average kinetic energy is
R ideal gas constant 8.314 J/K?mol T
temperature in Kelvin
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How fast do gas molecules move? Called the root
mean square speed of the gas.
in kg/mol
Equation gives speed in meters/second.
What is the rms speed of O2 molecules at room
temperature?
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Boltzmann Distributions
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Boltzmann Distributions and Molar Mass
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Boltzmann Distributions and Temperature
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Gas Diffusion
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Gas Effusion
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Grahams Law of Gas Effusion used for
determining molar mass of a gas
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Example A sample of ethane, C2H6, effuses
through a small hole at a rate of 3.6 x 10-6
mol/hr. An unknown gas, under the
same conditions, effuses at a rate of 1.3 x 10-6
mol/hr. Calculate the molar mass of the unknown
gas.