Solucionario Cap 14 - INCROPERA 7 Ed

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PROBLEM 14.3 
KNOWN: Partial pressures and temperature for a mixture of CO2 and N2. 
FIND: Molar concentration, mass density, mole fraction and mass fraction of each species. 
SCHEMATIC: 
 
 
 
 
 
 
2 AA CO , 44 kg / kmol→ =M 
 
2 BB N , 28 kg / kmol→ =M 
 
 
 
 
 
ASSUMPTIONS: (1) Perfect gas behavior. 
ANALYSIS: From the equation of state for an ideal gas, 
 ii
pC .
T
= ℜ 
Hence, with pA = pB, 
 A B 2 3
1 barC C
8.314 10 m bar / kmol K 298 K−
= =
× ⋅ ⋅ ×
 
 
 3A BC C 0.040 kmol / m .= = < 
With i i iC ,=Mρ it follows that 
 3 3A 44 kg / kmol 0.04 kmol / m 1.78 kg / mρ = × = < 
 
 3 3B 28 kg / kmol 0.04 kmol / m 1.13 kg / m .ρ = × = < 
Also, with 
 
 i i i ix C / C= Σ 
find 
 A Bx x 0.04 / 0.08 0.5= = = < 
and with 
 i i im /ρ ρ= Σ 
find 
 ( )Am 1.78 / 1.78 1.13 0.61= + = < 
 
 ( )Bm 1.13/ 1.78 1.13 0.39.= + = <