Exam%201%202007

Exam%201%202007 - Name Score BME 100L Exam 1 Fall 2007 1 A...

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Name: __________________________________ Score _________________ BME 100L Fall 2007 Exam 1 1. A sample consisting of 3 mol of a pure perfect gas is heated at a constant external pressure of 1 bar. Assume C V,m = 3.5R. The expansion is mechanically reversible; and there is no additional work on the gas. The initial temperature is 25 o C. When the gas volume triples, determine w, q, T, U, H, and S. (R = 8.314 J/K/mol,1 bar = 10 5 kg/m 2 /sec 2 , 1 J = 1 kg m/sec 2 ) Solution : p ex = 1 bar, p = p ex (since the expansion is mechanically reversible) V 1 = nRT 1 /p = 3*8.314*298/10 5 = 0.07433 m 3 V 2 = 3V 1 = 0.2230 m 3 dw = -pdV => w = -p V = -p2V 1 = -14.866 kJ T 2 = pV 2 /nR = 3pV 1 /nR = 3T 1 => T = 2T 1 = 596K U = nC V,m T = 3*3.5*8.314*596 = 52.029 kJ H = nC p,m T = 3*(3.5+1)*8.314*596 = 66.894 kJ q = U – w = H = 66.894 kJ S = nC p,m ln(T 2 /T 1 ) = 3*(3.5+1)*8.314*ln3 = 123.3 J/K
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2. The enthalpy of vaporization of chloroform (CHCl
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This note was uploaded on 01/17/2010 for the course BME 100 taught by Professor Yuan during the Fall '07 term at Duke.

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Exam%201%202007 - Name Score BME 100L Exam 1 Fall 2007 1 A...

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