Understanding Entropy Change in Irreversible Processes
The Second Law of Thermodynamics governs the direction of spontaneous processes and dictates the change in entropy.
Second Law of Thermodynamics and Entropy
- The Second Law states that for any spontaneous (irreversible) process, the total entropy of the universe always increases.
- Entropy ($S$) is a measure of the randomness or disorder within a system.
- The universe is composed of the system under consideration and its surroundings.
- The total entropy change of the universe is the sum of the entropy changes of the system ($\Delta S_{system}$) and the surroundings ($\Delta S_{surroundings}$).
Entropy Change Calculation
The total entropy change of the universe ($\Delta S_{universe}$) is expressed as:
$ \Delta S_{universe} = \Delta S_{system} + \Delta S_{surroundings} $
Condition for Irreversible Processes
For any process that occurs spontaneously or is irreversible:
- The total entropy change of the universe is always positive.
- Mathematically, for an irreversible process: $ \Delta S_{universe} > 0 $
Conclusion
Therefore, the statement that correctly describes the total entropy change of the universe during an irreversible process is that it is always greater than zero.
Important Questions from Second Law of Thermodynamics and Entropy
- Entropy of the universe is:
Change in entropy Δs in an isothermal process is
A system of 100 kg mass undergoes a process in which its specific entropy increases from 0.3 kJ/kgK to 0.4 kJ/kgK. At the same time, the entropy of the surroundings decreases from 80 kJ/K to 75 kJ/K.
The process is:A system undergoes a process such that \(\rm \displaystyle\int \frac{\delta Q}{T}=0\) and ΔS > 0, the process is
In order that a cycle be reversible, following must be satisfied
