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Unformatted text preview: CEM 383 Practice Exam 1 Fall 2007 1. The atmospheric pressure on the surface of Venus is 90 bar and it is
composed of 96% 002 and 4% of various other gases. The surface temperature of the planet is 730K. a) What is the partial pressure of C02 on the surface? I) . ’3 ' . ' .
(at XCcL' r1051: (4051‘s a b!!! V b) What mass of 002 is present per liter?
P 3 nilT ; was; RT V V “7,7 2. A mixture of CH4(g) and 02H5(g) is contained in a glass bulb of 0.5 L
volume at 25 °C. The total pressure is 1.25 bar and the mass of the gas in the bulb is 0.530 g. a) What is the average molar mass of the gas mixture? 051 rt? (. 013;?!“ m4)
Adm b) What is the mole fraction of CH4(g) in the bulb? Xfuq ( u’ + ‘ ch><30 : “1" Y HM +gU—30x  2/ y”?
H,<= <91
X: 0.3") 3. Use the Van der Waals coefficients given in the table below to label the
compressibility data with the appropriate gas identity, A, B or C. % albarLZ/molZ) b L/mol
A 0.21 0.0174
B 1.35 0.0386
C 4.25 ‘ 0.0380
N 1.0 4. The pressure of steam in a 20.0L tank at 400K is 14.0 bar. How long is
the time interval between collisions for a H20 molecule moving about in
this tank? The collision diameter for H20 (9) is 4.60 x 10‘10 m and R=0.083 Lbar/mol'K = 8.31 J/K°mo. I .. 7, . i A
{I‘vfnc{2(£§ zlv‘ﬂiz?
V ,gNltV 3  ‘5 I ' ‘ .4, (mlxlcl/JL
gﬁEW(L1.wxw'méYLr ii fi= 39—?  g V v lei (Maggi) (Lima) x) $3
14$
? £2 ityLU/l’gauwgf‘ H5
)5 S 40"?) t M/S : 1w no" 5—! b) How far does a water molecule travel during the time interval
calculated in part a? i i é‘i‘x lo "I 5 ‘/ 5. The Maxwell Boltzmann velocity distribution function for a molecule
\l“ ‘ming in a single dimension, x, is
f(vx) = (m/(2TrkBT))1/2 exp(—mvx2/(2kBT))
a) Write an expression for the maximum value that f(vx) can have. V1. 'F(vf\=<:f«ha_‘—_§ b) In class,we characterized the width of this distribution by determining
the values of vi at the points where f(v*) had fallen to e , or 36.8%
of its peak value. Derive the expression for the full width of the
distribution at its e11 points in terms of m, T and some constants. 2 if 1C6“); K m“. c“ ‘ NV: .
2.71167 I Lemmi < . 6. A cylinder with adiabatic, or insulating walls is filled with<Q§noles of an
ideal gas at P=0.3 bar and T=43OK. The initial volume is 11.9 L. The
system is suddenly compressed to a final volume of 1.0L by the Weﬂemal pressure to a piston that comprises one
"" end of the cylinder. Determine w, the work, for this process. (R=0.083
Lobar/moloK = 8.31 J/Kmol) V; l”
A): —f?¢,.ccil/   lxAdlf
., I
” um.
l.0L.
1" *lo‘ow V = ‘lo WOOL  ML)
lifil.
: “ (Cloak("(0 R < k} ’ L‘ ‘\\
) b) Calculate AU for this process. (CV = 3nR/2) Ll5¢\ : 4;)“: bH>—>(.W; ‘ LLSC‘VB
MIL 8760 K " H3C(. CT? = ‘l  ‘i ...
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 Fall '07
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