Chemical Reaction Engineering | Types of Reactions | GATE

  • Homogenous Reactions:

The reaction which is carried out in only one phase is called a homogenous reaction.

  • Heterogenous Reactions:

The reaction which is carried out in more than one phase is known as heterogenous reaction.

  • Reaction Rate :

The reaction rate can be defined on the basis of:

  1. Volume of reacting fluid:

r1

2. Unit of mass fluid :

r2

3. Volume of reactor :

r3

4. Surface of solid :

r4

5. Volume of solid:

r5

Reaction rate is dependent upon the rate of system i.e. :

  • temperature,
  • pressure and
  • composition.

Types of Reactions:

  • Single Reaction : When a single stoichiometric reaction and single rate equation is selected to represent the progress of reaction, it is called a single reaction.
  • Multiple Reaction : When more than one stoichiometric equation are used to represent the progress of reaction, it is called a multiple reaction.

Types of multiple reactions:

i. Series Reaction : 

r20

ii. Parallel Reaction :

(a) Competitive reaction

r23

(b) Side by side reaction

r19

(c) Parallel but in series

r18

Elementary Reaction:

The reaction in which rate depends upon stoichiometry of the reaction is called an elementary reaction.

e.g.r21

Non-elementary reaction :

The reaction in which rate does not depend upon stoichiometry of the reaction is called an non-elementary reaction.

e.g.

r22

r12

Forward Reaction:

If the reactant in the reaction is formed or produced the reaction is called a forward reaction.

Reverse Reaction:

If the reactant in the reaction is disappearing the reaction is called a reverse reaction.

e.g. r13

Here: r14 is rate of forward reaction and –r15 is the rate of reverse reaction written respectively as :

r16

It is important to remember that : r17

Chain Reaction:

1. Reaction Initiation :

r31

2. Reaction Propogation :

r32

3. Reaction Termination :

r33

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