SYSTEM & SURROUNDINGS
System refers to the part of universe chosen for our study
The portion of universe excluded from the system is called surroundings
Types of systems
open system
A system which can exchange both matter and energy with its surroundings is called open system.
Eg: hot coffee kept in a open vessel
Closed system
A system which can exchange energy but not matter is with its surroundings is called open system.
Eg: hot coffee kept in a closed vessel with conducting walls
Isolated system
A system which can neither exchange matter or energy with its surroundings is called open system.
Eg:hot coffee kept in a thermos flask
STATE FUNCTION & PATH FUNCTION
Property of a system depends only on the state of system and not depend on the path along which that state is attained is called state function
Eg:Pressure , volume , temperature
Property of a system which depends on the path along with the state is attained
is called path function
Eg: work, heat
INTENSIVE & EXTENSIVE PROPERTIES
Properties which are independent of amount of matter present in a system is called intensive properties
Eg:Pressure , viscosity , temperature
Properties which are dependent of amount of matter present in a system is called intensive properties
Eg: Mass, Volume , Energy
ENERGY OF A SYSTEM
Energy of a system is its capacity to do work. When a system does work, its energy is reduced and when work is done on a system its energy increases.
ADIABATIC & ISOTHERMAL PROCESS
A process in which no heat enters or leaves the system is called an adiabatic process. In such process the system is completely insulated from the surroundings.
An isothermal process is one which the temperature of the system remains constant throughout.In such a system energy can exchange to surroundings
ENDOTHERMIC & EXOTHERMIC PROCESS
process which liberates energy as heat is called an exothermic process
process which liberates energy as heat is called an exothermic process
REVERSIBLE PROCESS & IRREVERSIBLE PROCESS
A reversible process is one which is conducted infinitesimally slowly such that at every stage the driving force is only infinitesimally greater than the opposing force.. Such a process can be reversed by increasing the opposing force by an infinitesimal amount.
A process in which the driving force at any stage is greater than the opposing force is called an irreversible process.
All natural forces are irreversible.
INTERNAL ENERGY OF A SYSTEM(E)
The internal energy is the sum of total energies associated with the translational,rotational, vibrational,electronic, and nuclear motions at the molecular level as well as potential energy of interaction between constituent particles.
H=E+PV
A process in which the driving force at any stage is greater than the opposing force is called an irreversible process.
All natural forces are irreversible.
INTERNAL ENERGY OF A SYSTEM(E)
The internal energy is the sum of total energies associated with the translational,rotational, vibrational,electronic, and nuclear motions at the molecular level as well as potential energy of interaction between constituent particles.
ENTHALPY(H)
Enthalpy is the sum of internal energy and pressure volume energy.H=E+PV
THE ZEROTH LAW
Two systems that are both in thermal equilibrium with a third system are in thermal equilibrium with each other
FIRST LAW OF THERMODYNAMICS
Energy can neither be created nor destroyed it may be converted from one form to another
SPONTANEOUS PROCESS
A process which has a natural urge to take place by itself under a given set of conditions.
ENTROPY
Entropy is a measure of disorder or randomness in a system.
Greater the entropy greater the disorder
SECOND LAW OF THERMODYNAMICS
The entropy of the universe remains constant in a reversible process where as it increases in a irreversible process
GIBBS FREE ENERGY
It is the maximum amount of energy available with a system that can be converted into useful work or free energy the measure of the capacity of a system to do useful workG=H-TS(Gibbs -Helmholtz equation)
A process should be spontaneous only if the free energy change is negative.
JOULE THOMSON EFFECT
When a gas under high pressure is allowed to explain under adiabatic conditions through a porous plus in to a region of low pressure, there occur a change in its temperature. When a gas expands adiabatically some work is done by the gas to overcome the van der waals force of attraction between molecules.This is done at the cost of the kinetic energy of the gaseous molecules.Then the internal energy decreses the temperature decreases
