QUIZ_1v1+Solution

QUIZ_1v1+Solution - b) What is the relative change in...

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QUIZ #1 – 20 minutes Jan. 30, 2012 Name : ___SOLUTION __________________________________ A balloon filled with 0.1 moles of an ideal gas is moved from the surface of a water tank, where the pressure is 1 atm and the temperature is 25ºC, to a depth of 30 m where the pressure is 2 atm. Suppose this move is done reversibly and isothermally . Calculate the thermodynamic properties listed below. You are given that R = 8.314 J mol -1 K -1 = 0.0821 L atm mol -1 K -1 . Also, remember that T in Kelvin = T in Celsius + 273.15 Please, properly justify your answers! a) If the system consists of the gas in the balloon, is this an open, closed or isolated system, and why? Clearly system exchanges no material with the surroundings, so it must be closed or isolated. Also, because ΔT = 0, ΔE = 0 = q + w. We have a change in volume, so w≠0 and therefore q≠0 and the system exchanges heat with the surroundings. Therefore system is closed.
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Unformatted text preview: b) What is the relative change in volume of the system (in other words, what is V 2 /V 1 )? Ideal gas law: P 1 V 1 = nRT = P 2 V 2 since n and T are constant Therefore P 1 V 1 = P 2 V 2 and V 2 /V 1 = P 1 /P 2 = 1 atm / 2 atm = 0.5 c) What is E in Joules? E = C v T = 0 because T = 0 d) What is H in Joules? H = C p T = 0 because T = 0 e) What is (PV) in Joules? (PV) = (nRT) = nR (T) = 0 because T = 0 f) What is w in Joules? w = - p dV = - nRT dV = -nRT dV = -nRT ln (V 2 /V 1 ) V V w = - (0.1 mol) (8.314 J mol-1 K-1 ) (25+273.15) K (ln 0.5) = +172 J g) What is q in Joules? Which way is heat transferred (to the system or out of the system)? q = E w = 0 172 J = -172 J. Negative value means heat out of the system. You have to show your work. No partial credit for unsubstantiated answers!...
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This note was uploaded on 02/09/2012 for the course THERMO 306 taught by Professor Berthuiame during the Spring '11 term at Rutgers.

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