chem notes 10-12

chem notes 10-12 - 0.08206Latm/molK-PV = n(.08206)T-ex:...

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October 12, 2007 Dr. Stevens Gen. Chem. 1 Volume-amt. gas relationship -For 1 mol each at STP => -Ar = 22.09L -O2 = 22.40L -CO2 = 22.26L -Avg molar volume = 22.41L/mol (at STP) -about size of b-ball -if p and T are constant, then equal volumes of diff. gases contain the same moles -ex: find formula of a hydrocarbon if 1L CO2 reacts with 2L H2 to make 1L hydrocarbon + O2. -CO2 + 2H2 H4C + O2 CH4 = methane Empirical relationships: -V is indirectly proportional to p -V is proportional to T -V is proportional to n -therefore: V is proportional to nT/P -V = RnT/P PV = nRT (R = constant) -Ideal Gas Approximation -approximately true if p is low and V is large -R from V/n from Avogadro at STP conditions R = PV/nT = V/n x P/T = 22.414L/mol x 1atm/273K =
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Unformatted text preview: 0.08206Latm/molK-PV = n(.08206)T-ex: calc. p o 0.010mg N2 in a 5.0L tv tube at rm temp (23C).-p = (.08206)(300)(3.6x10^-7)/5 = 1.6x10^-6atm (near vacuum)-n = 0.010mg = 3.6x10^-7mol Speeds of molecules-Urms = root mean square speed-s = Urms = (u^2)^(1/2)-proportional to T-inversely proportional to MM-s = Urms = (3RT/MM)^(1/2)-on dist. Graph-max = avg. speed-speed most molecules have-KE = .5mv^2-kinetic energy of gases in same flask is equal-Urms (O2) at SATP-((3x8.314x302)/32)^(1/2) = 482m/s-R = 8.314J/molK Demo (balloon in N2(l)):-V/T = V/T-V1 = 1L, T = 302-T2 = -196 + 273-V2 = . 25L-how else could we reduce V to .25L?-change pressure (PV = PV)...
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chem notes 10-12 - 0.08206Latm/molK-PV = n(.08206)T-ex:...

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