 Thermo means heat and dynamics
means patterns of change.
 It is concerned with the study of
energy changes and the flow of
energy from one body to another
 It helps us to predict a specific
chemical reaction will occur based
on a particular set of conditions. In
other words, using this method
allows us to theoretically determine
if a chemical reaction will take
place given a set of specific
conditions.
 It is the study of “energy changes” taking place during chemical reactions
and physical processes reactions.
 It focuses on the energy changes taking place during chemical reactions
and physical processes reactions and interaction of the system and
surrounding
 System - It includes the molecules of interest.
 Surrounding - Everything that surrounds the system.
*In thermochemistry, we study the exchange of energy. It occurs between the
interaction of system and surroundings*
Matter exchange is the movement of molecules across the boundary of the
system and the surroundings.
Energy exchange are heat, work, and friction
Open System - matter and energy can
be exchanged with the surroundings
Closed System - exchange energy-but
not matter-with the surroundings
Isolated System - neither matter nor
energy may be exchanged with
surroundings
Exothermic Process is when heat/energy is released by the system into the
surroundings. (Ex. Burning of wood)
Endothermic Process is when heat/energy is absorbed by the system from
the surroundings. (Melting of ice)
Heat
 It is a form of energy that transfers
between a system and its
surroundings
because
of
a
difference in temperature between
them.
 The transfer of heat occurs from an
area of higher temperature to an
area of lower temperature until both
areas reach the same temperature
level, known as thermal equilibrium.
 If heat flows from a lower
temperature region to a higher
temperature region, work must be
applied to overcome the natural
tendency of heat to flow from high
to low temperatures.
Temperature
 It is a measure of average kinetic
energies of atoms and molecules of
a substance.
 The direction of heat is indicated.
When
a
system
and
its
surroundings have the same
temperature, the transfer of kinetic
energy stops.
Energy
 Calorie, which is a unit of energy change, is defined as the amount of energy
required to increase the temperature of 1.00g of water by 1 degree Celsius
(from 14.5 ºC to 15.5ºC)
 1 Calorie = 4.184 joule ( The SI unit of energy change)
 1 joule = 1 kg*m2/s
*Since joule (J) is a small unit, energy associated with chemical reactions are often
expressed as Kilojoule (Kj)*
Conversion of Energy
 Example of this is falling of brick.
 Potential Energy refers to the stored energy that an object possess
because of its position or arrangement. In this context, it could refer to
a brick that is high up and has the potential to fall.
 Kinetic Energy when the brick falls, its potential energy transforms
into kinetic energy, which is the energy of motion. The brick gains
kinetic energy as it falls, increasing its speed and its kinetic energy
 Light energy (sparks) when the brick hits the ground, it may
produce sparks, which are a form of light energy. The energy released
in this process can be seen in the form of light.
 Sound Energy (bang) The impact of the brick on the ground may
also produce a sound, which is a form of energy that travels through
the air as a vibration. The sound energy created by the impact of the
brick on the ground can be heard as a “bang”
 Chemical Energy (as the brick breaks) the final stage in this
process is the release of chemical energy as the brick breaks. When
the brick breaks, its bonds are broken, and energy is released in the
form of heat and light.
Thermodynamics can help us study how energy is converted to one from to
another.
Stability of molecules and direction of change
 Protein folding
 Proteins are polymer of amino acids that are link by polypeptide bonds.
This kind of polymer folds are lower temperature. Therefore, the structure
of protein will change if you change the conditions of the polymers.
Thermodynamics helps us understand the stability of structure and
biomolecules
Spontaneous Reaction
 if it occurs by itself
without
outside
assistance
 Under suitable conditions,
they proceed on their own
Non-spontaneous Reaction
 Not all reactions are spontaneous
like decomposition of water.
 For example, water will decompose
only by passing an electric current
through it. The reaction will continue
as long as the electric current is
maintained.
Reversible
 One which can be taken from
its initial state to another
state, and then back to initial
state without any change to
either the system or the
surroundings
 It is ideal and theoretical
Irreversible
 If process cannot be reversed
 It is a spontaneous reaction,
more natural, and increased
entropy