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38 Cards in this Set
- Front
- Back
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kinetic theory
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particles of matter are always in motion and that motion has consequences
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assumptions of kinetic theory
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gases have large number of particles; far apart; completely occupy container
constant particle motion; random directions at high speed no net loss of kinetic energy at constant temp and pressure in collisions between particles and walls no forces of attraction or repulsion between particles (except in real gases) average kinetic energy is proportional to absolute Kelvin temp of gas |
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why do gases expand?
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dont have definite shape or volume
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why do gases have fluidity?
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little attractive forces between particles so they slide easily past each other
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why do gases have low density?
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because particles are so far apart, density is lower
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Why are gases compressible?
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because they have a low density
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Why do gases diffuse?
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they have random motion, so the particles mix
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What does gas diffusion depend on?
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the velocity, diameter, and attractive forces between particles
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effusion
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process by which gas particles under pressure pass through a small opening from one container to another
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real gas
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gas that doesn't behave accordingly to the kinetic theory; occupies space and exerts attractive forces
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units of pressure conversions
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1 atm = 760 mmHg = 760 torr = 101.3 kPa = 1.013 bar = 14.7 psi
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what is STP?
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1 atm pressure, 273 K, 22.414 L/mol
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Boyle's Law
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at constant temperature, pressure inversely proportional to volume.
P1V1 = P2V2 |
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Charles' Law
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at constant pressure, volume directly proportional to kelvin temperature
V1/T1 = V2/T2 |
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Gay-Lussac's Law
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at constant volume, pressure directly proportional to temperature
P1/T1 = P2/T2 |
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Combined Gas Law
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P1V1/T1 = P2V2/T2
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Volume is ________ proportional to moles
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directly
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at a higher temperature, a gas occupies _____ volume, and thus becomes ________ dense
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more, less
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density at STP....
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is 22.414 L/ g
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Molar mass at STP =
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density (at STP) X molar volume
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ideal gas law
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relationship between pressure, volume, temp and # of moles of gas
PV=nRT |
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constant R equals....
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.0821 l(atm)/ mol(k)
or 8.31 J/mol (K) |
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d=
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m/V
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n=
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m/M
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density in ideal gas law
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d=MP/RT
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molarity in ideal gas law
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M=mRT/PV
or M=dRT/P |
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limitations of ideal gas law
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works well at low pressures and high temps
gases dont behave ideally above 1 atm does not work well near condensation conditions |
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volume to volume conversion
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gas volume A ------> gas volume B, using molar ratio as conversion
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volume to mass conversion
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gas volume A ----> moles A ----> moles B ---> mass B
or mass A ---> moles A--->moles B----> gas volume B |
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daltons law of partial pressures
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sum of partial pressures of all gases is equal to the total pressure of the mixture.... V and T are constant, partial pressure is dependent on number of moles of each gas
Ptotal = P1 + P2 + P3 +..... Pn P1= n1RT/V, same goes for P2 and P3 except they have n1 and n2 Ptotal = n1RT/V + n2RT/V + n3RT/V or Ptotal = (n1+n2+n3)RT/V |
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mole fraction
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represented by X... number of moles of a component in the mixture divided by total number of moles of all component in the mixture. X must be less than 1
x = molcomp/moltotal; no unit |
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partial pressure of a gas in a mixture is equal to....
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the mole fraction times the total pressure
Pcomp = xcompPtot |
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a gas collected over water has....
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a total pressure of the gas plus the pressure of the natural water vapor created due to evaporation
Ptotal = PH20 + Pgas |
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grahams law of effusion or diffusion
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rates of effusion and diffusion are governed by the velocities of gas molecules; velocity varies inversely with mass
rate of effusion of A/ rate of effusion of B = square root of Mb/Ma at same temp and pressure are inversely proportional to square roots of their molar masses rate of effusion A/rate of effusion B = Mb^1/2 divided by Ma^1/2 + densityb^1/2 divided by densitya^1/2 |
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root-mean-square speed
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u = square root of 3RT divided by M
R = 8.31 J/mol(K) M is determined in # kg/mol |
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the gas deviates from ideal behavior when the pressure is....
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high, usually above 10 atm
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the gas deviates from ideal behavior when the temperature from the gas is...
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low, and the gas is more liquid like
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in small volumes, _____ forces play a greater role
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attractive/repulsive
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