By Tasneem Ahmed
INTRODUCTION
Chemistry
•
A Branch of science which deals with the structure,
properties constituents and change which takes place is known as chemistry.
•
Origin of chemistry -: Chemes means black in colour. Egyptian called
black earth as “chemo ” and an early age the study of chemical science was
known as chemistry.
•
Antoine Lavoisier (1743, 1794) is known as the father of Modern Chemistry
NOTHING IS
LOST, NOTHING IS CREATED, EVERYTHING IS TRANSFORMED
What Is Physical
Chemistry?
If we look around us, chemical
reactions are taking place everywhere.
- When we strike a match to light our grills, a a chemical reaction occurs.
- If we mix milk with baking powder in our favourite recipe, a reaction happens.
- Why do some reactions create heat?
- How is it that certain reactions proceed fast while others move very slow?
- All these questions and more can be solved within the field of physical chemistry.
- The term "physical chemistry" was coined by Mikhail Lomonosov in 1752, according to him
PHYSICAL CHEMISTRY
•
The term "physical chemistry" was coined
by Mikhail Lomonosov in
1752
•
Physical Chemistry is the branch of chemistry dealing
with the principles and methodologies of both chemistry and physics and is the
study of how chemical structure impacts the physical properties of a substance.
Physical chemistry gives us information that how light behaves like a particle
in the form of Quantum. it also tells us that what sort of order of reaction a
molecule possesses?
•
it shows how ripening of fruits takes place
and what phenomenon is going on and how photons are get converted into mass.
how energy is produced from different resources and can be used for the benefits of
humankind.
•
Physical Chemistry includes the study of the physical
properties of many different types of substances and on different scales
(levels of physical detail).
•
That is, it includes the study of the following scales of
chemical properties of materials:
Macroscopic:
Macroscopic properties of substances describe how relatively massive quantities of the substance behave as a group,
Macroscopic properties of substances describe how relatively massive quantities of the substance behave as a group,
•
Example; melting points and boiling points, thermal conductivity, specific
heat capacity
Microscopic:
Microscopic properties of substances concern details of their physical properties observable only using the magnification provided by microscopes
Microscopic properties of substances concern details of their physical properties observable only using the magnification provided by microscopes
•
Example; the shapes and structures of crystals
Major Branches of Chemistry
Ø Physical Chemistry
Ø Analytical
Chemistry
Ø Biochemistry
Chemistry
Ø Organic Chemistry
Ø
Inorganic chemistry
SUB-BRANCHES OF
PHYSICAL CHEMISTRY INCLUDE
Ø Electrochemistry
(the study of the interaction of atoms, molecules, ions, and electric current)
Ø Photochemistry (the study of the chemical effects of light;
photochemical reactions)
Ø Surface chemistry (the study of chemical reactions at interfaces)
Ø Chemical Kinetics (the study of rates of chemical reactions)
Ø Thermodynamics/Thermochemistry (the study of how heat relates to chemical change)
Ø Quantum
Mechanics/Quantum Chemistry
(the study of quantum mechanics and how it relates to chemical phenomena)
Ø Spectroscopy (the study of spectra of light or radiation)
Thermodynamics/Thermochemistry
The word ‘thermodynamics’
comes from the two Greek words
Ø ‘dynamic’
comes from the Greek word dunamikos, which means movement
Ø thermo means energy or temperature i.e. ‘thermometer,’
“The branch of science that
deals with energy levels and the transfer of energy between systems and between
different states of matter”
Thermodynamics
is the scientific study of work, heat, and the related properties of chemical
and mechanical systems.
Thermodynamic System
An
an important concept in thermodynamics is the thermodynamic system. A
thermodynamic system is one that
interacts and exchanges energy with the area around it (transformation of energy). A system could be as simple
as a block of metal or as complex as a
compartment fire. Outside the system are its surroundings. The system
and its surroundings comprise the
universe.
Universe
Systems:
Ø A
region of the universe that we direct our attention to
Ø
part of the world has a special interest
Ø quantity of matter
Surroundings:
Ø Everything
outside a system is called surroundings
Ø where we make us
observation
Ø Everything other
than the system
Boundary:
Ø The
boundary or wall separates a system from its surroundings.
Ø imaginary or
a physical thing that separate system and surrounding
ENERGY TRANSFER IS STUDIED IN THREE TYPES OF SYSTEMS:
Open systems
Open systems can exchange
both matter and energy with an outside system. They
are portions of larger systems and in
intimate contact with the larger system. Your body is an open system.
Closed systems
Closed systems exchange
energy but not matter with an outside system. Though
they are typically portions of larger
systems, they are not in complete contact. The Earth is essentially a closed
system; it obtains lots of energy from
the Sun but the exchange of matter with the outside is almost zero.
Isolated systems
Isolated systems can
exchange neither energy nor matter with an outside system. While
they may be portions of larger systems,
they do not communicate with the outside in any way. The physical universe is an isolated system; a closed thermos
bottle is essentially an isolated system (though its insulation is not perfect).
Heat can be transferred between open systems and between closed systems, but not between
isolated
systems.
LAWS OF THERMODYNAMIC
The Zeroth Law
If
two thermodynamic systems are each in thermal equilibrium with a third, then
they are in thermal equilibrium with each other.
Two systems that are each
found to be in thermal equilibrium with
a third system will be found to be in
thermal equilibrium with each other.
•
The Zeroth law is so named as
it came after the other 3. Laws 1, 2, and 3 had been around for a while before
the importance of this law had been fully understood. It turned out that this
law was so important and fundamental that it had to go before the other 3, and
instead of renaming the already well known 3 laws they called the new one the
Zeroth law and stuck it at the front of the list.
•
it gives you information about mass/energy.
•
I assume the water bucket in which you put a cup of tea …
so if the water is in thermal equilibrium with tea. And tea is in thermal
equilibrium with surrounding then you have to say water is in equilibrium with surrounding.
That is what zeroth law is
•
If A=B and C=B, then A=C. This may seem so obvious
that is do not need stating but without this law, we could not define
temperature and we couldn’t build thermometers.
First law of thermodynamics
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Energy can neither be created nor destroyed. It can
only change forms. In any process, the total energy of the universe stays the
same. For a thermodynamic cycle, the net heat supplied to the system equals the
network done by the system.
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The first law of thermodynamics states that energy is
conserved; it can neither be created nor destroyed, just changed from one for
to another,
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“The total amount of energy in an isolated system is
conserved.”
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it is simply saying that energy is conserved. You
neither create energy nor destroy energy.
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The energy in a system can be converted to heat or
work or other things, but you always have the same total that you started with.
•
As an analogy, think of energy as indestructible
blocks. If you have 30 blocks, then whatever you do to or with the blocks you
will always have 30 of them at the end. You cannot destroy them, only move them
around or divide them up, but there will always be 30. Sometimes you may lose
one or more, but they still must be taken account of because Energy is
Conserved.
Second law of thermodynamics
The entropy of an isolated system not in equilibrium
will tend to increase over time, approaching a maximum value at equilibrium
There is no such device which develops 100% work.
Nothing is in the world which convert energy one form to another form with no such
losses. There must be some losses. And that is why no one is 100% efficient.
Entropy and enthalpy
Both entropy and enthalpy are thermodynamically
properties of a system.
Entropy is a measure of disorder or randomness of a system. An ordered system has low entropy. A disordered system has high entropy.
Entropy is a measure of disorder or randomness of a system. An ordered system has low entropy. A disordered system has high entropy.
Enthalpy is defined as the sum of internal energy of a system and the
product of the pressure and volume of the system. The change in enthalpy is the
sum of the change in the internal energy and the work is done.
Enthalpy and entropy are different quantities. Enthalpy has the units of heat, joules. Entropy has the units of heat divided by temperature, joules per kelvin.
Enthalpy and entropy are different quantities. Enthalpy has the units of heat, joules. Entropy has the units of heat divided by temperature, joules per kelvin.
Third Law of Thermodynamics
As
temperature approaches absolute zero, the entropy of a system approaches a
constant minimum.
•
This is the most famous (among scientists at least)
and important laws of all science. It states;
“The
the entropy of the universe tends to a maximum.”
•
In other words, Entropy either stays the same or gets
bigger, the entropy of the universe can never go down. There is no such device
which has zero entropy. The third law provides an absolute reference point for
measuring entropy, saying that
“As
the temperature of a system approaches absolute zero (−273.15°C, 0 K), then the
value of the entropy approaches a minimum.”
•
The value of the entropy is usually 0 at 0K, however
there are some cases where there is still a small amount of residual entropy in
the system.
Summary of The Laws of Thermodynamics
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0. This is the Game: you are here, you are
part of the system
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1. You Cannot Win: you cannot get more
energy out of the system than you put into it.
•
2. You Cannot Break Even: any transfer of
energy will result in some waste of energy unless a temperature of absolute
zero can be achieved.
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3. You Cannot Get Out of the Game: you
cannot achieve absolute zero.
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Stated simply: There is no such thing as a free lunch.
Reference
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http://www.vidyagyaan.com/general-knowledge/science/basic-chemistry-element-terms-and-definitions/
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https://images.app.goo.gl/XrGqyrjf2KR9MwA59
