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Unformatted text preview: ChE 210: Meeting 16 February 18, 2011 Outline (F&R Sections 5.35.5) Homework Due Friday 02/25/2011
 Tc and Pc 5.12, 5.16, 5.25, 5.30, 5.69, 5.74  Nonideal Equations of State
 Compressibility Factor  Law of Corresponding States
 Mixtures of Nonideal Gases Critical Temperature (Tc) and Pressure (PC)
 All gases are nonideal at low T (< O C) and high P (> 1 atm)  Using the ideal gas law could give errors in V by a factor of 2 — 3  Critical temperature and pressure help determine if use of the ideal gas
law is appropriate I Determination of TC and PC: LowP ‘ Fixed T
All vapor 2 Low P '
Fixed T
Vapor & liquid rﬁzf‘ﬁss‘mﬁ) {svékgfmg } W 1 25.9 i £33329 1:933:35; 997.9
:2 ms t 1.9:} mm 9525.?
3 2.31.4 i 35.3; mm was
a 349.3 163: 113.3 5331}: ~ w
:5: 373.? 21’s.: 3,633 6 3?:135 1 2523.3. m5 313.5 33?4415 Ne canderzsaiirm warm! 1/6 ChE 210: Meeting 16 February 18, 2011 Gas vs. Vapor:  Vapor — exists at T < TC and can be condensed to a liquid isothermally  Gas — exists at T > T0 and P low enough that p is closer to a vapor (~1
g/L) than a liquid (~1000 g/L) Nonideal Eguations of State A Virial: ﬂ=1 + E
RT RT
B = EEO + (DB1)
PC
Van der Waals: P = ART — v—{b‘ 1V2 2/6 ChE 210: Meeting 16 February 18, 2011 RT da SoaveRedlichKwong: P = A  A A
V—b V V+ b 5 Com pressibility Factor *for an ideal gas 2 = 1
**z for several components tabulated in Perry’s Handbook Law of Corresponding States Values of certain physical properties (including 2) depend on the proximity
of a gas to a critical state ‘ " To use compressibility factor equation of state for unknown V:
1.) Look up TC and Pc 2.) Calculate Tr and Pr
3.) Look up 2 on generalized compressibility chart A 4.) Calculate V 3/6 ChE 210: Meeting 16 February 18, 2011 To use compressibility factor equation of state for unknown P or T:
1.) Look up Tc and PC
2.) Calculate Tr or Pr A ideal
3.) Calculate Vr = A V PC
RTC 4.) Look up 2 on generalized compressibility chart
5.) Calculate P or T Example 5.42 One hundred grammoles of nitrogen is contained in a 5liter vessel at 
20.6 C. Estimate the pressure of the cylinder. Given: 1; .m‘. x rm 1‘  u ._ .. .;_ a: r Find: Physical Properties: l l 33 f
at It ,‘u “ A2> ; Emmy Solution: 4/6 ChE 210: Meeting 16 February 18, 2011 :12 W Fir? KT
{A3
b n
s» 290 Gmtprwsimmy {21mm ﬂatmates! gamma: ﬂ, _/‘»,
' "w e
if: N : _ t x!
V 15,: \l ;. \ \
:\
'1
t 1
3 ’ \ ,' \ V ‘
‘ w 4 x a x 1. \ ‘\ lkar l)k‘
~  y 1 1
‘ "Hi 1.»
'2: , ‘_.
3 lg 5/6 ChE 210: Meeting 16 February 18, 2011 Mixtures of Nonideal Gases Kay's Rule estimates pseudocritical properties *works best for mixtures of nonpolar compounds with Tc’s and P53 within a
factor of 2 6/6 ...
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 Spring '02
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