Department of Chemical Engineering
University of California, Santa Barbara
Problem Set No. 3
Due: Wednesday, January 19, 2011
To understand and perform calculations using the First Law of Thermodynamics,
and to assess system energy flows in closed systems.
Numerical values for some problems have been changed from those in the book.
Problem 7 (thought problem)
A friend claims that the work required to compress steam, in general, can be evaluated by
looking up enthalpy and other property values before and after the compression in tables (e.g.,
the steam tables at the back of your book).
What is wrong with this assessment?
What if the
compression is known to be isobaric, specifically?
Problem 8 (
Smith, van Ness, Abbott, 2.8, page 57)
A closed, nonreactive system contains species 1 and 2 in vapor/liquid equilibrium. Species 2 is a
very light gas, essentially insoluble in the liquid phase. The vapor phase contains both species 1
and 2. Some additional moles of species 2 are added to the system, which is then restored to its