Question

What is entropy and why is it important for the understanding of thermodynamics?

Answer 1

The most way to explain it is to say that it describes the natural tendency of the universe to fall apart into disorder. A well known illustration is the messy room concept. You know that you need to constantly work at keeping your room clean and well arranged. However, you know that if you don’t keep up with the routine the room will gradually return to its messy state.


However, entropy has other meanings and applications as well. It can also mean the state of a thermodynamic process. Essentially, this is the inertia that makes a thermodynamic process more likely to occur. Certain reactions and processes occur more often because the larger value of entropy in the system of the reaction. Any reaction that releases energy can be considered to experience an increase in its entropy.

Like pushing a boulder down a hill thermodynamic reactions will continue until it reaching equilibrium a barrier that prevents the reaction from continuing. Entropy is an aspect of the reaction that can be used to measure this.

Answer 2

Entropy is a measure of 'order' or 'level of organisation' of a system. This implies that 'a system' can have different levels of organisation, like two different gasses in a single container, separated by a screen. If you remove the screen, the gasses will not stay neatly separated (entropy is high) but will wander around until each gas more or less uniformly distributed over the available space (entropy is at it's lowest). Therefore, entropy is a measure for the tendency of a system to change state in a certain direction.

Answer 3

The tendency of the system or a reaction to proceed in a particular known direction is called as entropy of the system. It is basically a term of disorder or randomness. Rudolf Clausis coined this term.
Entropy is a very important thing in the realm of thermodynamics. It's the core idea behind the second and third laws and shows up all over the place.

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