IMPORANT POINTS
FROM THE VIDEOS
SECOND LAW OF
THERMODYNAMICS :
SPONTANEOUS REACTION
AND ENTROPY
•No input energy required for spontaneous processes.
•Energy is transferred between system and surroundings as work and heat
but , energy remains conserved.
•Second law tells nothing about spontaneity of a process.
•Enthalpy can be used to tell that, but it cant be considered sufficient .
•As per enthalpy, exothermic processes are spontaneous since they have
negative enthalpy.
•And endothermic aren’t ,as they have negative enthalpy.
AGAIN ENTHALPY ISN’T SUFFICIENT TO TELL THAT !!!
•Entropy is related to number of microstates, directly proportional to its
natural logarithm.
•The grater the number of possible arrangements for a given system , the
greater the number of its microstates and hence its entropy.
•Two types of entropy : position and thermal , based on particle’s
distribution according to space and temperature respectively in a system
.
•Second law quantifies entropy.
•Acc to entropy studies, change in entropy is positive for a spontaneous
process and is negative for non spon. one.
The particles are distinguishable here , while talking about microstates.
ENTROPY,MICROSTATES
AND BOLTZMANN EQUATION
•Positive change in entropy means that the system is evolving from a
system of low number of microstate(less porobable) to a system of large
number to microstates(more probable).
•Microstate are instantaneous property of a system. Ex: instantaneous
position and velocity of gas molecules .
•Number of microstates can be increased by increasing the volume or
temperature.
•Boltzmann related microscopic microstates to the macroscopic
thermodynamic state using relation S= KB LnΩ .
•If volume of a system is increased P times and N is the number of
distinguishable particles, then total number of final microstates will be
given as PN