Does the entropy per cycle increase, decrease, or remain the same for (a) a Carnot refrigerator, (b) a real refrigerator, and (c) a perfect refrigerator (which is, of course, impossible to build)?
Entropy change is a phenomenon that quantifies how disorder or randomness has changed in a thermodynamic system. From the processes followed by given refrigerators, we can decide about the entropy.
A Carnot refrigerator is an ideal refrigerator. All processes are reversible and there is no wastage of energy due to friction and turbulence. The entropy per cycle remains the same for reversible processes.
Hence, entropy remains the same for a Carnot refrigerator.
A real refrigerator loses energy due to the friction. This is an irreversible process. Therefore, the entropy of this refrigerator increases.
A perfect refrigerator transfers heat energy from the cold reservoir to the hot reservoir. Therefore, the entropy of a perfect engine decreases, that is negative which violates the second law of thermodynamics.
Suppose 4.00mol of an ideal gas undergoes a reversible isothermal expansion from volume to volume at temperature T = 400 K . (a) Find the work done by the gas and (b) Find the entropy change of the gas (c) If the expansion is reversible and adiabatic instead of isothermal, what is the entropy change of the gas?
Expand 1.00 mol of a monatomic gas initially at 5.00kPa and 600 K from initial volume to final volume . At any instant during the expansion, the pressure p and volume V of the gas are related by , with p in kilopascals, and V in cubic meters, and . (a) What is the final pressure and (b) what is the final temperature of the gas? (c) How much work is done by the gas during the expansion? (d) What is for the expansion? (Hint: Use two simple reversible processes to find .)
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