Chem 20b midterm

# Chem 20b midterm - I Gases& Kinetic Theory Ideal Gas –...

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Unformatted text preview: I. Gases & Kinetic Theory Ideal Gas – provides connection between macro and microscopic worlds such as pressure and temp • Have mass, zero volume • Collisions elastic • No force of attraction SI Units of pressure = force/area • Pascal , 1 Pa = 1 Nm-2 • Atmosphere, 1 atm = 101.325 kPa; 1 atm = 760 mmHg at 0 ° C • Torr, 1 Torr = 1/760 atm • 1 bar = 100kPa • P = hpg; h is height, p Is density, g is gravity Boyles Law • V ∝ 1/p; PV = k • Physics of breathing follows Boyles Law; volume of lungs increase and decrease as diaphragm moves Charle’s Law • V ∝ T; V/T = k • As a gas is heated it expands, All gases show 0 volume at 0 K Avagadro’s Law • V ∝ n; V/n = k Combine three gas laws to get PV = nRT R constant • 8.31451 J/(molK) • .08206 atmL/(molK) Molar Density = n/V Molar Volume = V/n Dalton’s Law • If there is a mixed gas, the total pressure is the sum of the partial pressures from the different components • P i = χ i P tot , where χ I is moles of I divided by total # of moles Kinetic Theory • Relate the temperature with Kinetic energy of gases • KE = 32 PV; KE = 32 nRT • V (r.m.s.) = 3RT μ MOLAR MASS IN kg • Molar thermal energy: 32RT • Particle thermal energy : 32KbT • Each degree of freedom adds 12KbT Collisions – gas particles colliding with each other • Average distance between collisions called mean free path = Vr.m.s. x time between collisions •...
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Chem 20b midterm - I Gases& Kinetic Theory Ideal Gas –...

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