Resolving the Paradox of Entropy and Energy

[kntsy]

If the air conditioner is reversible engine but not carnot, will the entropy(total) still increase? I think YES, but college physics text says entropy(total) remain constant for reversible?

Anyone can answer this brainteaser?

 

[Drakkith]

I thought entropy was relative to the ultimate state of disorder in a given system with isolated inputs. So, if a system reaches thermal equilibrium at on temperature, it has reached maximum entropy because no more disgregation of heat will take place. If heat is added unevenly, entropy can decrease insofar as the heat is concentrated/aggregated within some subset(s) of the system. In that case, the heat will dissipate and eventually cause the system to reach thermal equilibrium, but this time at a higher temperature.

Is this an incorrect description/example of thermal-equilibrium progress as increasing entropy?

Yes that looks correct.

 

[Dickfore]

we know that when the energy drops the entropy increases

but the entropy should DECREASE AS LONG AS THE ENERGY INCREASES.
where is my mistake?

How did you come to these conclusions? Where do we know this from?

 

[Andrew Mason]

I thought entropy was relative to the ultimate state of disorder in a given system with isolated inputs. So, if a system reaches thermal equilibrium at on temperature, it has reached maximum entropy because no more disgregation of heat will take place. If heat is added unevenly, entropy can decrease insofar as the heat is concentrated/aggregated within some subset(s) of the system. In that case, the heat will dissipate and eventually cause the system to reach thermal equilibrium, but this time at a higher temperature.

Is this an incorrect description/example of thermal-equilibrium progress as increasing entropy?

Entropy has meaning only in terms of the difference in entropy between two states. As heat flows into the gas, there is a positive change in entropy of the gas (and a smaller negative change in the entropy of the surroundings).

"Disorder" is not really a very accurate explanation for entropy. First of all, it is not clear what "disorder" means. Consider 2 moles of gas in equilibrium at temperature T. Then consider one mole of the same gas at temperature T + \Delta T and the other mole at T - \Delta T. Which of these two states has the most disorder? Why?

Second, a concept of "disorder" is misleading. Consider a mole of He gas and a mole of Argon gas each at state (P,V,T) in its own compartment insulated from their surroundings separated by a common insulated wall. Then consider the situation where the wall is removed and the gases mix. Is there a change in entropy? Do both states represent the same amount of disorder?

AM