exam_final - 10.40 Thermodynamics Final Exam 3 hr 9 am 12...

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10.40 Thermodynamics Final Exam 3 hr, 9 am – 12 noon Use of Thermodynamics and Its Applicati ons, 3 rd ed. and 10.40 class notes and handouts and a hand calculator are permitted. No other aids or documents are permitted. Please answer each question in a separate exam book. Be careful about managing your time and be aware of the maximum points allotted to each part of the 5 problems. 1. (20 points) Rocky and Rochelle Jones are having one of their heated arguments on thermodynamics. This time they are trying to reconcile the theoretical and empirical underpinnings of the so-called K factor charts or nomographs that were used during the last century, before computers were readily available, to characterize equilibrium phase partitioning in multicomponent distillation of hydrocarbons. K is defined as the equilibrium ratio of a particular component y i in the vapor phase to x i in the liquid phase. A typical nomograph is shown below for a set of light alkane and alkene hydrocarbons -- C-1 (methane) through C-9 (nonane), Rocky claims that the K factors do a reasonable job of capturing important non- idealities over a wide range of conditions. In fact, Rocky notes that you only need the temperature and pressure to specify the vapor liquid equilibrium state as indicated by the nomograph. By connecting a straight line to a specific T and P, the intersection of that line with curve for each compound yields the K = y i /x i . Rochelle adamantly maintains that the K’s are only based on single component information and that they fail to include intermolecular interactions. We need your help to settle this argument. (a) (10 points) Derive a general relationship for K in an n -component system vapor- liquid mixture at equilibrium. Clearly indicate the functional dependence of all derived parameters on measurable properties and state what type of constitutive property relationships are needed to evaluate K for each component. (b) (10 points) For the P and T conditions given in the nomograph, who do you think is correct, Rocky or Rochelle? Explain.
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 10.302 taught by Professor Clarkcolton during the Fall '04 term at MIT.

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exam_final - 10.40 Thermodynamics Final Exam 3 hr 9 am 12...

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