Zeroth Law of Thermodynamics
Zeroth Law of Thermodynamics
states that "that if two systems are at the same time in thermal equilibrium with a third system, they are in thermal equilibrium with each other."
If A and C are in thermal equilibrium with B, then A is in thermal equilibrium with B. Practically this means that all three are at the same temperature,
and it forms the basis for comparison of temperatures.
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Many observations of real gases have shown that the difference of the heat
flow into the gas and the work done by the gas depends only on the initial and
final states of the gas and does not depend on the process or path which produces
the final state. This suggests the existence of an additional variable, called the
internal energy of the gas, which depends only on the state of the gas and not on any process.
The internal energy is a state variable, just like the temperature or the pressure. The first law
of thermodynamics defines the
internal energy (E) as equal to the difference of the heat transfer (Q)
into a system and the work (W) done by the system.
E2 - E1 = Q - W
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Many texts define the second law as
"the entropy of the universe increases during any spontaneous
process."
OR
Energy spontaneously disperses from being localized to becoming spread out if it is not hindered from doing so.
What is Entropy ???
Entropy measures the spontaneous dispersal of energy: how much energy is spread out in a process, or how widely spread out it becomes — at a specific temperature.
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