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19 Cards in this Set
- Front
- Back
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Ideal gas |
no intermolecular forces and occupy no volume |
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Real gases |
deviate from ideal behavior at high pressure (low volume) and low temperature |
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Ideal gas law |
PV=nRT |
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Ideal gas constant R |
8.21x 10^-2 L.atm/mol.K 8.314 J/L.mol |
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Density and ideal gas law |
density = m/V = PM/RT M = molar mass M = density at STP x 22.4 L/mol |
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Avogadro's principle |
n1/V1 = n2/V2 |
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Boyle's Law |
P1V1=P2V2 |
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Charle's Law |
V1/T1 = V2/T2 |
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Gay-Lussac's Law |
P1/T1 = P2/T2 |
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Dalton's law of partial pressures |
Pt = Pa + Pb + ... Pa = XaPt Xa = moles of gas A / total moles of gas |
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Henry's Law
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[A]1/P1 = [A]2/P2 |
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Assumptions of kinetic molecular theory |
1. Gases are made up of particles with volumes that are negligible compared to the container volume 2. gas atoms or molecules exhibit no intermolecular attractions or repulsions 3. gas particles are in continuous, random motion, undergoing collisions with other particles and the container walls. 4. collisions between any two gas particles are elastic, meaning that there is conservation of both momentum and kinetic energy 5. the average kinetic energy of gas particles is proportional to the absolute temperature of the gas, and it is the same for all gases at a given temperature, irrespective of chemical identity or atomic mass |
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Average kinetic energy of a gas particle |
KE = 1/2 mv^2 = 3/2 kb T kb = boltzmann's constant = 1.38 x 10^-23 J/K |
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Root-mean square speed |
urms = sqrt (3RT/M) M=molar mass more molecules are moving at higher speeds at higher T |
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Graham's law of diffusion and effusion |
All gas particles have the same average kinetic energy at the same temperature, so particles with greater mass travel at a slower average speed (based on the root-mean square equation) r1/r2 = sqrt (M2/M1) |
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Effusion |
the flow of gas particles under pressure form one compartment to another through a small opening. Relationship is the same as that for diffusion: r1/r2 = sqrt (M2/M1) |
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Real gases: deviations due to pressure |
Moderately high pressure: volume is less than would be predicted due to intermolecular attraction. Extremely high pressure: volume is greater than would be predicted since the size of the particles becomes relatively large compared to the distance between them. |
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Real gases: deviations due to temperature |
As T decreases, average speed decreases and intermolecular forces become increasingly significant. Condensation temp approaches. At moderately low temperature, occupies less volume than predicted. At extremely low temperature, occupies more volume than predicted. |
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Van der Waals equation |
(P + n^2a/V^2)(V - nb) = nRT a = corrects for the attractive forces between molecules (large for larger and more polarizable gases) b = corrects for the volume of the molecules themselves (larger for larger molecules) |
