3) Second Principle Of Thermodynamics Entropy Flashcards
Significance of the second principle
Determines the direction of thermodynamic process
Declares some of the process to be impossible
Reversible thermodynamic process
The system can return to its initial state by passing through the intermediate states cause no change to environment
Irreversible thermodynamic processes
The system can return to initial stage only if work is performed by external force
All real processes are irreversible
The second principle (Clausius)
Heat can’t flow from a colder to hotter body
As cooling is an irreversible process
Cyclic process
Cycle is a thermodynamic process which ultimately returns the system to its original state along a new path
Work done by cyclic process
A cyclic process doesn’t change the internal energy of the system
Q-A=🔺U=0
Efficiency
The ratio between the work A done by the system and the amount of heat Q received by the system
The second principle (Thomson)
No cyclic process can convert heat into work by cooling a body with this being the only result
Reduced heat
Reduced heat is Q/T
Q is the best output and input
T is the temperature
Graph is sad curve on v and p graph
The second principle (Carnot)
Q1 is the heat input at temperature T
Q2 is the heat input at T2
Q1/T1+ Q2/T2 is less than 0
Multiplicity
Is the number of microstates through which s macrostate can be realised.
Entropy
Is the measure of disorder within a system
Increased entropy means increased disorder and ability to perform work decreases
Eg melting ice as disorder of water molecules increases
The second principle- entropy and reduced heat
Ds=s1-s2 is greater thank &q/T
Same graph sad curve with p and v on axis
S1 then &q then s2
The second principle in isolated systems- entropy
I’m isolated systems no process can decrease entropy
Reversible reactions don’t change entropy
Irreversible reactions increase entropy
Gibbs free energy
G= H- TS
T is temp
G is free energy
Helmholtz free energy
F = U- TS
The second principle and dissipation of energy
An irreversible process that decreases the free energy of the system
Reversible processes don’t change the free energy
Types of process by the change of free energy
Exergonic is a spontaneous process that produced work and the free energy decreases
Endergonic it the non spontaneous process that uses woke and free energy increases
Biological systems and steady states
All biological systems are open
All biological systems sustain steady stage
Steady state is when thermodynamic variables are constant regardless of process taking place
Entropy of open system
Ds= dsi + dse
Change due to irreversible process taking place
Change due to interaction of system with environment
Constant entropy at steady state
This does not change regardless of the irreversible processes taking place
Ds = 0
This is due to interaction of the system with environment
Overall entropy of a biological system and its environment
Entropy of biological system is constant
Order in the biological system is preserved by disorder in the environment increases
The second principle for biological systems
Ds/dt = dsi/dt + dse/dt
Homeostasis
Is the steady state of living biological systems
The maintenance on internal conditions within humans
Equilibrium and steady states
Eq state
No energy and matter exchange with the environment
Steady state
Continuous exchange of energy and matter with the environment
