2. •Charles, Hill. G.
(1977). An introduction
to chemical engineering
kinetics & reactor design.
John Wiley & Sons.
Reference Book
https://drive.google.com/file/d/0B3XI7_
a2_fthRUl0ZEw3OEtTS00/view?usp=shar
ing
3. Chapter 3: Basic Concepts in Chemical Kinetics –
Determination of the Reaction Rate Expression
The rate of a chemical reaction (r) defined as;
Several facts about this definition:
• r is an intensive variable
• The definition is independent of particular reactant or product
• Since the reaction rate changes with time, it is necessary to use
time derivative to express the instantaneous rate of reaction
4. Extent of reaction: Changes in the mole numbers ni of
the various species involved in a reaction are related
to the extent of reaction by the following equation
5.
6. Variables that can influence the rate of reaction are;
•System temperature, pressure, composition
•Properties of catalyst (that may be present)
•System parameters that govern the various physical
transport processes (i.e. the flow condition, degree
of mixing, heat & mass transfer parameters of the
system)
7. Rate Expression:
• Where, φ(Ci ) is a function that depends on the concentration of
various species (reactants, products, catalysts and inhibitors)
• φ(Ci ) may also depend on the temperature
• The coefficient “k” is called reaction rate constant. It is independent
of the composition and is consequently independent of time for an
isothermal system
• The rate constant “k” generally varies with the absolute temperature
of the system according to Arrhenius equation;
where
E = apparent activation energy
R = universal gas constant
A = pre-exponential factor, sometimes called the frequency factor,
which is assumed to be a temperature independent quantity
Rate Constant, k
8. The manner in which the reaction rate varies with the
concentrations of the reactants and products is
indicated by stating the order of the reaction.
Reaction Orders
9. When one reactant is present in large excess, the
amount of material that can be consumed by reaction
is negligible compared to the total amount present.
Under these circumstances, its concentration may be
considered constant throughout the reaction.
r= k CA
βACB
βBCC
βC
= k’ CB
βBCC
βC
K’ = apparent/empirical pseudo rate constant
Pseudo-Rate Constant
10. First order reactions in Constant Volume system
By integration subject to the condition that ξ* = 0 at t = 0 gives
