Module - 1
Chemical Thermodynamics
and Kinetics
Chemical Thermodynamics and Kinetics
Chemical Thermodynamics:
laws of thermodynamics –
entropy change (selected processes) – spontaneity of a
chemical reaction and Gibbs energy – Carnot cycle.
Chemical kinetics: Order of reactions – Concept of
activation energy, energy barrier – Arrhenius equation –
homogeneous, heterogeneous and Enzyme catalysis (Lock
and Key Mechanism).
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Thermodynamics and Chemical Kinetics
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Thermodynamics and Chemical Kinetics
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Chemical Thermodynamics
Thermodynamics:
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Thermodynamics and Chemical Kinetics
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Chemical Thermodynamics
Thermodynamics:
•
The word “Thermodynamics” is composed of
two words, namely “Thermo” and “Dynamics”.
➢ Thermo – Stands for heat
•
•
➢ Dynamics – Used in connection with
mechanical motion which involves
“Work” done
Thus, Thermodynamics is the branch of science and engineering which deals
with process involving heat, work and energy
In broad terms, thermodynamics deals with the transfer of energy from one
place to another and from one form to another.
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Thermodynamics and Chemical Kinetics
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Chemical Thermodynamics
Chemical Thermodynamics:
• Chemical thermodynamics is the study of the
interrelation of heat and work with chemical reactions.
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Thermodynamics and Chemical Kinetics
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Basic Terminologies of Thermodynamics
• There are several basic principles of chemical thermodynamics to
consider:
i.
Systems
ii. Laws of thermodynamics
iii. Enthalpy
iv. Heat capacity
v. Specific heat capacity
• Chemical thermodynamics is also concerned with four particular
quantities:
1. Internal energy
2. Enthalpy
3. Entropy
4. Gibbs free energy
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Thermodynamics and Chemical Kinetics
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Basic Terminologies of Thermodynamics
• There are several basic principles of chemical thermodynamics to
consider:
i.
Systems
ii. Laws of thermodynamics
iii. Enthalpy
iv. Heat capacity
v. Specific heat capacity
• Chemical thermodynamics is also concerned with four particular
quantities:
1. Internal energy
2. Enthalpy
3. Entropy
4. Gibbs free energy
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Thermodynamics and Chemical Kinetics
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i. System
i. System
➢ Part of the universe which under investigation
• Types of System
1. Open system
A System which can exchange both energy and
matter with surrounding
2. Closed System
A System which permits passage of energy but
not matter, across its boundary
3. Isolated system
A System which can exchange neither energy
nor matter with its surroundings
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i. System
State of a system
• The state of thermodynamic variables such as pressure,
temperature, volume, composition which describes the system is
called state of the system.
Four kinds of
processes
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i. System
• Properties of a system
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Thermodynamics and Chemical Kinetics
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Basic Terminologies of Thermodynamics
• There are several basic principles of chemical thermodynamics to
consider:
i.
Systems
ii. Laws of thermodynamics
iii. Enthalpy
iv. Heat capacity
v. Specific heat capacity
• Chemical thermodynamics is also concerned with four particular
quantities:
1. Internal energy
2. Enthalpy
3. Entropy
4. Gibbs free energy
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Thermodynamics and Chemical Kinetics
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iii. Laws of thermodynamics
0. Two bodies in thermal
equilibrium are at same T
1.
Energy can never
created or destroyed
be
2. The total entropy of the
UNIVERSE must increase
in every spontaneous
process
3. The entropy of a pure,
perfectly
crystalline
compound at T = 0 K is
Zero.
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0. Zeroth (0th) law of thermodynamics
Why Zeroth (0th) law?
Ralph H Fowler
discovered the title “Zeroth law of thermodynamics”
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0. Zeroth (0th) law of thermodynamics
Why Zeroth (0th) law?
• No one was knowing about the term “temperature” before 1935.
• All the three laws of thermodynamics (first, second and third law) were
already discovered before 1935.
• In 1935, Fowler discovered the title “Zeroth law of thermodynamics”
and thermal equilibrium.
• Fowler realized that this phenomenon of thermal equilibrium is very
important and it should be discussed before the first law of
thermodynamics
• But already so many books were published with the first law, second law
and third law. Now changing the number of these three laws can create a
lot of confusion.
• Thus, he was forced to adopt the number “zero” for his law.
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0. Zeroth (0th) law of thermodynamics
“If two systems are in thermal equilibrium with a third
system, then they are in thermal equilibrium with one
another”
A
C
B
TA
Tc
TB
After a while
TA
Tc
TA
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TC
TB
TB
Thermodynamics and Chemical Kinetics
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1. First
st
(1 )
law of thermodynamics
• The first law of thermodynamics, also known as “Law of
Conservation of Energy”
“It states that energy can neither be created nor
destroyed; energy can only be transferred or changed from
one form to another”
• For example, turning on a light would
seem to produce electromagnetic
energy; however, it is electrical energy
that is converted.
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