Page 54 - Elements of Chemical Reaction Engineering Ebook

Chap. 1 Queslions and Problems 25

SUMMARY
1. A mole balance on species j, which enters, leaves, reacts, and accumu-
lates in a system volume r! is

(Sl-1)

2. The kinetic rate law for rj is:
0 Solely a function of properties of reacting materials [e.g., concentra-
tion (activities), temperature, pressure, catalyst or solvent (if any)].
0 An intensive quantity.
0 An algebraic equation, not a differential equation.
For homogeneous catalytic systems, typical units of -rj may be
gram moles per second per liter; for heterogeneous systems, typical
units of rj may be gram moles per second per gram of catalyst. By
is
convention, -rA is the rate of disappearance of species A and I-, the
rate of formation of species A.
3. Mole balances on four common reactors are as follows:

Reactor Mole Balance C40mment

Ta CSTR v=- Fj, - F, No spatial variation
No spatial variation,
steady state
- rj
Steady state

Steady state

QUESTIONS AND PROBLEMS

I wish I had an answer for that, because I’m getting
tired of answering that question.
Yogi Bema, New York Yankees
Sports Illustrated, June 1 1, 1984
The subscript to each of the problem numbers indicates the level of difficulty: A,, least
Before solving difficult; D, most difficult.
the problems,
state or sketch
qualitatively the
expected results In each of the questions and problems below, rather than just drawing a box around your
or trends. answer, write a sentence or two describing how you solved the problem, the assump-
tions you made, the reasonableness of your answer, what you learned, and any other
facts that you want to include. You may wish to refer to W. Strunk and E. B. White, The
Elements of Style: (New York: Macmillian, 1979) and Joseph M. Williams, Style: Ten
Lessons in Clarity di Grace (Glenview, Ill.: Scott, Foresman, 1989) to enhance the qual-
ity of your sentences.