This document discusses key concepts in chemical kinetics including: 1) Chemical kinetics deals with the rates of chemical reactions and their mechanisms. 2) The rate of a reaction is defined as the decrease in reactant concentration or increase in product concentration over time. 3) The order of a reaction refers to the power to which the concentration of a reactant is raised in the rate law expression.

1. 1
QURATULAIN MUGHAL
BATCH IV
DOCTOR OF PHYSICAL THERAPY
ISRA UNIVERSITY

2. 2
CHEMICAL KINEMATICS
DEFINITION:
“the branch of physical chemistry which
deals with the rate of chemical reactions
and the mechanism through which they
occur is called chemical kinematics”

3. 3
RATE OF REACTION
• DEFINITION:
“the decrease in concentration of reactant or
increase in concentration of the products
of the reaction at a given moment of time
is called rate of reaction”
FORMULA:
dx/dt=K

4. 4
CONTI…..
• Where,
dx=change in concentration
dt=time taken for change
K= reaction rate constant

5. 5
ORDER OF REACTION
• DEFINITION:
“the number of reacting molecules whose
concentration alters as a result of chemical
change is called the order of reaction”
OR
“the sum of exponents in the rate expression of a
reaction is the order of reaction”
OR
“the power to which concentration of reactant is to
be raised to get the rate of reaction”

6. 6
CONTIN……
• EXAMPLES:
mA+rB product
rate = K[A] ͫ [B] ͫ
The oder of reaction= (m+r)

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TYPES OF ORDER REACTION
1. First order reaction
2.Second order reaction
3.zero order reaction

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FIRST ORDER REACTION
• If a reaction rate depends on a single
reactant and the value of the exponent is
one, then the reaction is said to be first
order.
• r = k [A]
• FORMULA:

9. 9
FIRST ORDER REACTION

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SECOND-ORDER REACTION
• the rate of reaction is directly proportional
to the square of the concentration of one
of the reactants.
• r = k [A]2

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ZERO-ORDER REACTION
• For a zero-order reaction, the rate of
reaction is a constant. When the limiting
reactant is completely consumed, the
reaction abrupt stops.
• r = k

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