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29 Cards in this Set
- Front
- Back
-ideal gas law -two prostulates of the ideal gas law |
-predicts the relationship between pressure volume and temperature and amount of gas 1)gas molecules have zero volume 2)there are zero intermolecular forces between bass molecules |
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gas constant (R) |
measure of thermal energy in a gas |
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STP SATP |
STP T=273.15K (0 degrees) P=1 bar SATP T= 298.15k (25 degrees) P= 1 bar |
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getting concentration from ideal gas law |
n/v - concentration (moles over volume) therefore: P/RT =concenteration |
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density using ideal gas law |
(mass over volume) P/RT = (n.M)/v |
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daltons law of partial pressure |
states that we can consider each gas in a mixture independently. total pressure is just the sum of all partial pressures |
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partial pressure is proportional to |
concentration |
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partial pressure when collisions are reactive and non reactive |
when collisions are non reactive it does not matter what two molecules collide. gas mixtures behave the same as pure gas. when collisions are reactive, the partial pressure of the entities is important . |
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as altitude increases temperature |
first decreases... then starts to increase (most likely due to the ozone) then decreases again and starts to increase again ( this time most likely reaching the end of the atmosphere) |
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as altitude increases pressure |
decreases |
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relative humidity (RH) |
is a measure of the amount of water vapour in the air Pressure increases as temperature increases |
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Ptotal = |
Pdry air+ ph20 (important in solving questions) |
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acid rain |
produced because of nitrogen and sulfur combustion |
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energy: E*= Erms= |
all entities have energy by virtue of their temperature E= 2.45 kj/mol Erms=3.72kj/mol |
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Kinetic molecular theory (KM) three points |
the KM theory explains the gas laws points: 1) gas consists of molecules with a mass "m" and a diameter "d" in constant random motion 2) molecular diameter is negligible in comparison to the distance between molecules. 3) all collisions are elastic there is no loss of kinetic energy and no reaction |
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maxwell Boltzmann distribution |
energy collisions redistribute the thermal energy between colliding entites |
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drawing the maxwell boatsman distribution for velocity, order from highest peak to lowest |
o2, n2 h2o, he , h2 |
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temperature thermodynamics perspective |
measure of rms energy in a substance (thermal energy) |
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pressure caused by increases with |
caused by molecules colliding with the walls of the container pressure increases with more gas: collisions are more frequent higher temperature- gasses hit the wall with more energy |
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diffusion |
passage of gas through another substance along a concentration gradient in hot water is faster---> more energy |
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effusion |
passage of a gas through a small orifice (hole) into a vacuum |
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real gasses recall the two postulates of the ideal gas law not true anymore |
real molecules have finite volume. zero volume postulate fails at high pressure have attractive intermolecular forces zero intermolecular postulate fails at low temperature ( low temperature gas condenses |
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compressibility Z |
is a measure of the non ideal behaviour of gas Z= PV / nRT look at compressibility chart |
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van der waals equation Parameter "b" b gets bigger as the |
approximately corrects for the failings of the ideal gas law finite volume: assume each mole of gas molecules occupy volume "b" Vactual = Vcontainer - nb as the molecule gets bigger |
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parameter "a" in van der waals equation |
intermolecular forces: the parameter "a" accounts for the intermolecular interactions Pobserved = Pideal - a(n/v)^2 n/v -----> concenteration |
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van der walls equation |
formula sheet gasses section third equation left side |
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entities at the wall experience |
net attractive forces towards the other entities |
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how does "a" and "b" effect pressure |
rearrange van der walls equation to se this clearly. "a" causes pressure to go down |
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when doing van der walls questions |
pay attention to the units -----> use the right value for R everything should cancel. |