Question

Know what is meant by entropy and how certain processes are irreversible (e.g. heat flow into the environment, many phase changes, mixing of two substances initially separated) lead to changes in entropy while certain ideal cyclic processes not.

Know the relationship between reversible and irreversible processes and how to recognize whether a process is reversible or not. Please give an example of each

Answer 1

Entropy is a theoretical concepts that is used to determine the feasibility of process to occur.

( Entropy is not a measurable quantity , you can't measure jt by experiment ) purely theoretical concepts.

According to the laws of thermodynamics

Entropy in a process should always increase or remain constant but it should never decrease in a process.

in other words we say entropy is a measure of randomness.

More random system means more entropy

example - A gas in a container is less random in comparison with a gas which is open to enviornment.

And in the context of reversibility or irreversibility

If a system is becoming less random automatically which means entropy is decreasing but as i mentioned entropy should never Decrease so a process which is becoming less random automatically is a irreversible process

example A open gas can't come into a container automatically.

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