Page 158 - Elements of Chemical Reaction Engineering 3rd Edition

130 Isothermal Reactor Design Chap. 4

volume remains constant, we also have V = Vo. Consequently, for constant-vol-
ume (V = V,) (e.g., closed metal vessels) batch reactors the mole balance

can be written in terms of concentration.

Generally, when analyzing laboratory experiments it is best to process
the data in terns of the measured variable. Since concentration is the measured
variable for most liquid-phase reactions, the general mole balance equation
applied to reactions in which there is no volume change becomes

Mole balance

We consider the reaction

which is irreversible and second order in A. The rate at which A is being con-
sumed is given by the rate law

Rate law -rA = kCi (4-3)
We combine the rate law and the mole balance to obtain

Initially, CA = CAO att = 0. If the reaction is carried out isothermally, we can
integrate this equation to obtain the reactant concentration at any time t:

Second-order,
isothermal,
liquid-phase (4-5)
batch reaction cA