Question

State the various statements of the Second Law of Thermodynamics.

Answer 1

The 1st order of thermodynamic states that energy can not be destroyed or created but it can be interchanged from one to another. So, the first order reaction gives information about the energy transfer process. But it cannot explain the direction of energy transfer, so this is where the second law of thermodynamics is introduced.

Complete step by step answer:
The second law of thermodynamic states that, for any natural process, the entropy will increase for a spontaneous reaction.
This concept of entropy is used to measure the spontaneity of any process or change of the system. According to the second law of thermodynamics for an isolated system( no exchange of heat or mass with the surroundings) the reversible process always proceeds to increase the entropy.
Therefore, from this law, it is concluded that any process would be spontaneous if the entropy is increasing through that process. For example, the melting of ice is a spontaneous process, as due to the melting of ice entropy of the system increases.
Here $\Delta S$ is a change of entropy. Entropy is a state function of any system. It is only depending upon the initial and final state of the system throughout a process but does not depend upon the pathway of the process.
The mathematical representation of the second law of thermodynamics is $\Delta {S_{universe}} > 0$ .
When the entropy of the final state of any process is higher than the initial state, the change of entropy .i.e. $\Delta S$ becomes positive. And when the entropy of the final state of any process is lower than the initial state, the change of entropy .i.e. $\Delta S$ becomes negative.
Now the change of entropy indicates the change of disorders of the randomness of the system. So, if the change of entropy $(\Delta S)$ is positive then the system becomes more disordered.

Note:
In a close system, the mass of the system remains constant. During the heat exchange with surroundings. This exchange creates a disturbance in the system and it causes an increase in entropy of the system. Also, the internal energy of the system changes due to the movement of molecules which increases the entropy.