Oregon State University Chemistry Exam 2 - Ideal Gas Thermodynamics, Exams of Physical Chemistry

Download Oregon State University Chemistry Exam 2 - Ideal Gas Thermodynamics and more Exams Physical Chemistry in PDF only on Docsity! E X A M KEY Oregon State University Department of Chemistry Chemistry 440 Hour exam 2 14 November 2007 Do not turn to page 2 of this exam until told to do so. dU(S, V , ni) = TdS - PdV + C pidni - AH - TAV PlV: = P2V2 adiabatic process y = Cp/Cv 1 bar = lo5 Pa 1 L = lop3 rn3 Process a 0 (nl2) process b 0 I Processc 3 lo 0 AU AS 1. (18 pts) Calculate m, and for the following processes which involve one mole of an ideal gas at an initial temperature T. Here env denotes the environment or the surroundings. (a) The gas is expanded isothermally and reversibly from 15 t o 30 L. (b) The gas is expanded isothermally against zero pressure as the volume increases from 15 to 30 L. (c) The gas is compressed adiabatically and reversibly until its temperature reaches P T . Note C, = % R, C, = q R. 4. (8 pts) The Helmholtz energy of a fluid is given by n2 A(n, V, T) = -a- - nRT ln(V - nb) + f (T) v (5) where a and b are constants and f (T) is a function of temperature. Determine the pressure of the fluid. 5. (8 pts) Calculate the change in Gibbs energy when 40 g of liquid ethanol (mass density of 0.80 g/cm3) when the pressure is increased by 200 bar. 6. (8 pts) The vapor pressure of a liquid obeys where the pressure is measured in units of bar and the temperature in Kelvin. Derive numerical values for the normal boiling point temperature and AH,,. In class comments, to see if you were listening 7. (8 pts) Shown below is the Otto cycle. Describe the real world significance of the following: . s t e p 3 1 4 , y h b + ( ~ S ~ P step 4 -+ 5 p m s + o ' ~ 8. (8 pts) (a) Sketch G(T, P) vs T for a single component under constant pressure in the vicinity of the liquid-gas phase transition. Label each phase. (b) Define a first order transition for the above example using the Ehrenfest criterium. 9. (2 pts) Many functions in thermodynamics carry the name of the originator, Gibbs functions, Helmholtz energies, etc. We use A to denote the Helmholtz energy in respect for the unfortunate accident that took the life of little Arbeit, his first son. True ".i)