PracticeEx1_Solution

PracticeEx1_Solution - class Problem 5 You can calculate Δ S(gas if you know V i and V f 3 5 049884 10 300 314 8 2 m P nRT V i i i = × × = = 3 5

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Problem 1. (a) False : Thermodynamics can be applied only to a system with many particles (b) True : Δ H = q in an isobaric process. (c) False : System does Maximum work in the reversible process. (d) True (e) False : In a spontaneous process, total S Δ > 0. sys S Δ can increase, decrease or stay. (f) True : total S Δ is larger for the irreversible process. But sys S Δ is the same for both irreversible and reversible processes, thus surround S Δ is larger for the irreversible one. Problem 2. (a) ) ( i f V V P V P w = Δ = = - 1 atm × 2 L = - 101325 Pa × 2 × 10 -3 m 3 (SI unit) = -203 J (b) i f i i Vf Vi i f Vf Vi V V V P V V nRT dV V nRT PdV w ln ln = = = = = - 1 atm × 1 L × ln3 = - 101325 Pa × 1 × 10 -3 m 3 × ln3 (SI unit) = -111 J Problem 3. ( ) nRT nb V V n a P = Ο Ο Π Ξ Μ Μ Ν Λ + 2 2 2 2 V n a nb V nRT P = ( ) ) 1 1 ( ln ln 2 2 2 2 2 2 i f i f Vf Vi V V V V V V V V rev V V an nb V nb V nRT V n a nb V nRT dV V n a dV nb V nRT dV V n a nb V nRT PdV w f i f i f i f i = Υ Φ Τ ΢ Σ Ρ = Ο Ο Π Ξ Μ Μ Ν Λ + Ο Π Ξ Μ Ν Λ = Ο Ο Π Ξ Μ Μ Ν Λ = = Problem 4. Same questions as Prob.6 in HW2. Solution will be given on 9/26/22 in

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Unformatted text preview: class. Problem 5. You can calculate Δ S (gas ) if you know V i and V f . 3 5 049884 . 10 300 314 . 8 2 m P nRT V i i i = × × = = 3 5 016628 . 10 4 400 314 . 8 2 m P nRT V f f f = × × × = = Then, K J R K K R V V nR T T C gas S i f i f V / 11 05 . 0166 . ln 2 300 400 ln 2 2 3 ln ln ) ( − = × × + × × × = + = Δ To calculate S (surround ), you need to calculate q . This is an irreversible process. Since the external pressure is 4 bar during the process, you can calculate w if you know Δ V. J V V P w i f ex 4 . 13302 ) 05 . 0166 . ( 10 4 ) ( 5 = − × − = − − = J R T T C U i f V 2 . 2494 100 314 . 8 3 ) 300 400 ( 2 3 2 ) ( = × × = − × = − = Δ J w U q 2 . 10808 4 . 13302 2 . 2494 − = − = − Δ = S (surround) = - q / T = 10808.2 / 400 = 27 J/K...
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This note was uploaded on 09/25/2011 for the course CH 353M taught by Professor Lim during the Fall '08 term at University of Texas at Austin.

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PracticeEx1_Solution - class Problem 5 You can calculate Δ S(gas if you know V i and V f 3 5 049884 10 300 314 8 2 m P nRT V i i i = × × = = 3 5

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