Page 124 - Elements of Chemical Reaction Engineering 3rd Edition

96 Rate Laws and Stoichiometry Chap. 3

TABLE 3-4. CONCENTRATIONS IN A VARIABLE-VOLUME GAS FLOW SYSTEM

Example 3-6 Manipulation of the Equation for q. = hi (X)

Show under what conditions and manipulation the expression for C, for a gas flow
system reduces to that given in Table 3-4.

Solution
For a flow system the concentration is dejned as

(E3-6.1)
From Table 3-3, the molar flow rate and conversion are related by

(E3-6.2)

Combining Equations (E3-6.1) and (E3-6.2) yields
FAO[@B - (b/a)Xl
C, = (E3-6.3)
U
This equation for u
is only for a gas- Using Equation (3-44) gives us
phase reaction
u = uo(l +EX) - - (3-44)
p To

to substitute for the volumetric flow rate gives

(E3-6.4)

FAO
Recalling - CAo, we obtain
=
UO