Name: Absolute Zero and Third Law of Thermodynamics
Uploaded: 2019-07-19
Duration: 20 min
Description: In this video, you will learn what absolute zero and the third law of thermodynamics is. You will also learn about the significance of the third law of therm...

Question

What are the limitations of the first law of thermodynamics? State second law of thermodynamics in as many ways as you can.

Accepted Answer

A major limitation of the first law of thermodynamics is that it merely indicates that in any process, there is an exact equivalence between the various forms of energies involved. But it provides no information concerning the spontaneity or feasibility of the process, i.e., whether the process is possible or not.

For example, the first law does not indicate whether heat can flow from a cold end to a hot end or not. All that it tells is that if this process occurred, the heat energy gained by one end would be exactly equal to that lost by the other end.

Similarly, the first law does not tell whether a gas can diffuse from low pressure to high pressure or water can itself run uphill etc.

Statements of second law of thermodynamics:

All spontaneous processes (or naturally occurring processes) are thermodynamically irreversible.

Without the help of an external agency, a spontaneous process cannot be reversed, e.g., heat cannot by itself flow from a colder to hotter body.

The complete conversion of heat into work is impossible without leaving some effect elsewhere.

All spontaneous processes are accompanied by a net increase of entropy, i.e., for all the spontaneous processes, the total entropy change (sum of the entropy changes of the system and the surroundings) is positive.

The entropy of the universe is continuously increasing.

What are the limitations of the first law of thermodynamics? State second law of thermodynamics in as many ways as you can.

Important Questions on Thermodynamics

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