This preview shows page 1. Sign up to view the full content.
Unformatted text preview: CHEM131 Homework n°2 1. Levine 2.1 a. The kinetic energy of a system of several particles equals the sum of the kinetic energies of the individual particles. True b. The potential energy of a system of interacting particles equals the sum of the potential energies of the individual particles. False 2. Levine 2.13 a. For every process, ∆Esyst = ∆Esurr.  True For any process: ∆Esyst + ∆Esurr = 0 b. For every cyclic process, the final state of the system is the same as the initial state.  True c. For every cyclic process, the final state of the surroundings is the same as the initial state of the surroundings.  False. Final and initial states refer only to the system and not to the surroundings. d. For a closed system at rest with no fields present, the sum q + w has the same value for every process that goes from a given state 1 to a given state 2.  True. The sum of q + w = ∆U, that is a state function of the system. e. If systems A and B each consist of pure liquid water at 1 bar pressure and if TA > TB, then the internal energy of system A must be greater than that of B.  False. ∆U= q + w 3. Levine 2.24 a. The quantities H, U, PV, ∆H, and P∆V all have the same dimensions.  True. All of them have the same dimensions: work (energy) b. ∆H is defined only for a constant pressure process.  False. It can also be defined for constant volume process for condensed phases at moderate pressures. c. For a constant volume process in a closed system, ∆H= ∆U  False. ∆H= ∆U for condensed phases not at high pressures. 4. Levine 2.42 a. A thermodynamic process is defined by the final state and the initial state.  False. A thermodynamic process is defined by series of thermodynamic states through which the system passes on its way from the initial state to the final state. b. ∆T =0 for every isothermal process.  True. In an isothermal process, T is constant throughout the process; therefore ∆T =0. c. Every process that has ∆T =0 is an isothermal process.  False. ∆T =0 can also occur in cyclic process. d. ∆U=0 for a reversible phase change at constant T and P.  False. ∆U= q + w for a reversible phase change. e. q must be zero for an isothermal process.  False. q ≠ 0 in an isothermal process. f. ∆T must be zero for an adiabatic process.  False. q = 0 but not ∆T. 5. Levine 2.45 a. Reversible melting of solid benzene at 1 atm and the normal meting point. b. Reversible melting of ice at 1 atm and 0°C. c. Reversible adiabatic expansion of a perfect gas. d. Reversible isothermal expansion of a perfect gas. e. Adiabatic expansion of a perfect gas into a vacuum (Joule experiment). f. Joule Thomson adiabatic throttling of a perfect gas. g. Reversible heating of a perfect gas at constant P. h. Reversible cooling of a perfect gas at constant V. q w ∆U a. + + b. + + + c. 0 d. + 0 e. 0 0 0 f. 0 0 0 g. + + h. 0  ∆H + + 0 0 0 +  6. Levine 2.67. A student attempting to remember a certain formula comes up with C p Cv = TVαm/κn, where m and n are certain integers whose values the student has forgotten and where the remaining symbols have their usual meanings. Use dimensional considerations to find m and n. Cp Cv = TVαm/κn , where m and n are integers. Dimensions of the physical quantities: The powers of temperature in each side of the equation are: For n, So the powers of energy in each side of the equation are: 7. A sample consisting of 2.0 mol of a monoatomic perfect gas, for which Cv,m= 3R/2, initially at P1= 1.50 atm and T1= 300K is heated reversibly to 400K at constant volume. Calculate the final pressure, ∆U, q, and w. a. Final pressure b. ∆U c. Work, w d. Heat, q 8. A sample of argon mass of 6.56g occupies 18.5L at 305K. a. Calculate the wo rk done when the gas expands isothermally against a constant external pressure of 7.7 kPa until its volume is increased by 3.5L. b. Calculate the work that would be done if the same expansion occurs reversibly. a. Isothermal expansion a constant external pressure b. Work when the expansion occurs reversible. 9. Consider a perfect gas contained in a cylinder and separated by a frictionless adiabatic piston into two sections, A and B; section B is in contact with a water bath that maintains it at constant temperature. Initially TA = TB = 300 K, VA = VB =2.00 L, and nA = nB = 3.00 mol. Heat is supplied to Section A and the piston moves to the right reversibly until the final volume of Section B is 1.00 L. Calculate (a) the work done by the gas in Section A, (b) ΔU for the gas in Section B, (c) q for the gas in B, (d) ΔU for the gas in A, and (e) q for the gas in A. Assume CV,m = 25.0 J K−1 mol−1. a. Work done by the gas in section A b. ΔU for the gas in Section B c. q for gas in B. d. ΔU for the gas in A e. q for the gas in A. 10. Let z = x/(1 + y2). Find dz. 11. Determine whether or not dz = xydx + xydy is exact by integrating it around the closed curve formed by the paths y = x and y = x2 between the points (0, 0) and (1, 1). Note: while there are other ways to determine whether dz is exact, want you to do it this particular way. 1. x= y 2. y= x2 Since each path gives different results; dz in not an exact differential. ...
View
Full
Document
This note was uploaded on 02/07/2011 for the course CHEM 131 taught by Professor Lindenberg during the Spring '08 term at UCSD.
 Spring '08
 Lindenberg

Click to edit the document details