DL Activity 4.4.2

DL Activity 4.4.2 - (B) Almost Reversible Processes a) The...

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Irreversible and Reversible Processes: 2nd Law of Thermodynamics (A) What is the difference between a reversible and an irreversible process? We know that, while the amount of energy in the universe is finite, so energy is always conserved, the entire universe is always tending towards disorder. So an irreversible process would increase the amount of entropy in the universe, and wouldn't spontaneously reverse itself. A reversible process wouldn't change the amount of entropy in the universe, so going from state A to state B wouldn't be favored over going from state B to state A. Man-made processes (and most processes, in general) are irreversible. We lose energy to friction (which is thermal energy, which is associated with the RANDOM motion of particles) and increase the entropy of the universe.
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Unformatted text preview: (B) Almost Reversible Processes a) The total change in entropy = (change in entropy of system A) + (change in entropy of system B) The total change in entropy = (heat transferred to system A)/(Temp of A) + (heat transferred from system B)/(Temp of B) The total entropy change for Case I is about .004 J/K The total entropy change for Case II is about .0001 J/K b) Case I is clearly irreversible, we've gained a noticeable amount of entropy. Case II, by comparison, is nearly reversible, we've had a very small increase in entropy. c) Based on this example, to have a nearly reversible process you have to transfer only small amounts of heat between very small differences in temperature, and not lose any energy to friction. This implies that reversible processes occur slowly, and in small increments....
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