Homework 1 and 2 - 1 Please estimat constants a and b in...

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Unformatted text preview: 1. Please estimat constants a and b in the Deterici equation by the critical condition of CO2. Deterici equation: At the critical condition: 0, 0 + + 0, = 0, 0, 1 0, 0, 0, 0, , 2 2 for CO2: Tc=304.3 K, Vc=95.7 (cm3mol-1), Pc=7.41MPa 47.85 (cm3mol-1) = 4.785×10-5 (m3mol-1) 2 8.314 304.13 95.7 10 0.484 2. Plot Z vs. P at 300 and 400K for CO2 if the P-V-T relation can be described by Deterici equation. Deterici equation: From practice 1 0.484 300 8.314 300 4.785 10 Try Vm= 0.0000485 m3 . , . 4.785 10 (m3mol-1) P = 702 atm New Vm , z = 1.365 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 100 300K 400K Z 200 300 400 500 600 700 800 900 Presure (atm) 3. Estimate the Boyle temperature for CO2 if the P-V-T relation can be described by Deteric equation. Deterici equation: 1 1 1 1 1 2! B= =0 0.484 4.785 10 1216.61 8.314 4. Try to calculate Zc if the P-V-T relation can be described by Deterici equation. Deterici equation: From practice 1 2 2 0.271 , 2 P7.3) At 500 K and 400 bar, the experimentally determined density of N2 is 7.90 mol L–1. Compare this with values calculated from the ideal and Redlich-Kwong equations of state. Use a numerical equation solver to solve the Redlich-Kwong equation for Vm or use an iterative approach starting with Vm equal to the ideal gas result. Discuss your results. For the ideal gas, 1 P 400 bar = = = 9.62 mol L? ? ? ? Vm RT 8.314 × 10 L bar K mol × 500 K PRK = RT a 1 − Vm − b T Vm (Vm + b ) 8.314 × 10 ? L bar K ? mol ? × 500 K 400 bar = Vm − 0.02208 L mol ? 1 17.40 L2 bar mol ? K 2 1 − Vm Vm + 0.02208 L mol ? 500 K ( ) The three solutions to this equation are Vm = ( −0.00529 ± 0.0186i ) L mol ? and Vm = 0.1145 L mol ? Only the real solution is of significance. 1 1 = = 8.73 mol L? ? Vm 0.1145 L mol The ideal gas density is greater than that calculated with the Redlich-Kwong equation of state and the experimental result showing that the repulsive part of the potential dominates. The Redlich-Kwong result is in error by +10%. P7.6) Calculate the Redlich-Kwong parameters of methane from the values of the critical constants. 5 a= R 2Tc 9 Pc 2 3 − 1 b= ( ( 2 1 2 3 − 1 RTc 3Pc 1 ) ) (8.314 ×10 = = ? dm3 bar K ? mol ? 9 × 45.99 bar 2 3 − 1 ( 2 3 − 1 × 8.3145 × 10 ? dm3 bar K ? mol ? × 190.56 K 3 × 45.99 bar = 0.02985 dm3mol ? 1 ) ( ) × (190.56) 2 5 2 1 ) = 32.20 dm bar K mol−2 6 1 2 ...
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This note was uploaded on 11/11/2010 for the course CHE CH2005 taught by Professor 曹恒光 during the Spring '10 term at National Central University.

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