what is entropy?

@essa-6maQw2 • Oct 26, 2024

Oct 26, 2024

1.3K

I am a mechanical engineer and I want someone among you to explain me the term entropy and relate it to enthalpy. Why and how is it used? I want to know it in detail. Please explain.

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Kedar Malwadkar

@kedar-crbktt • Jun 24, 2012

In simple Entropy is a thermodynamic property of a system which increases with addition of heat and decreases with removal of heat.
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Kedar Malwadkar

@kedar-crbktt • Jun 25, 2012

enthalpy = internal energy + flowwork
enthalpy and entropy are two different properties of system.
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Ramani Aswath

@ramani-VR4O43 • Jun 25, 2012

Different types of energy have different levels of availability. Even in one kind of energy, say heat, the level of temperature decides the availability of that heat for usable work.
Entropy is a quantitative expression of the degree of unavailability of energy. Greater the unavailability greater the entropy.
Generally all natural (spontaneous) processes are more or less irreversible. Entropy is a measure of this irreversibility. For example water flows down hill by itself. You need a pump to push it back up. By losing potential energy in flowing down water increases its entropy.
Heat flows from a higher to a lower temperature by itself, not the other way One needs a heat pump (such as refrigerator) to push heat the other way.
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The myth buster

@the-myth-buster-WdRWjO • Jun 25, 2012

well entropy determines that whether or not a process occurs..and if possible then the direction in which it shall proceed.."Entropy" is not a simple word which just signifies randomness rather is determines the closeness of one process to being reversible..i.e entroy determines the extent of reversibility.
The more the degree of reversibility the lower the entropy rise.For a completely reversible process,the entropy change is zero i.e entropy remains the same.Most of the real life processes are irreversible and so there is always some entropy chane associated with them.The aim of an engineer is to reduce this change or increase in entropy level.
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