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bill nye scienceguy!
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if there is a decrease in pressure at constant temperature will there be an increase in entropy?
Maybe...bill nye scienceguy! said:if there is a decrease in pressure at constant temperature will there be an increase in entropy?
The only way to have a decrease in pressure at constant temperature is to have an increase in volume. Work must be done in order to increase the volume (unless it is a free expansion). From the first law, if temperature remains the same (ie. internal energy remains constant) there must be heat flow into the gas. Since entropy is dQ/T, and dQ is positive (ie. into the gas) there is an increase in entropy of the gas.bill nye scienceguy! said:if there is a decrease in pressure at constant temperature will there be an increase in entropy?
Andrew Mason said:From the first law, if temperature remains the same (ie. internal energy remains constant) there must be heat flow into the gas
But in this case, temperature is constant. I am not aware of any substance which, if pressure is decreased its volume reduces. So if pressure decreases and temperature is constant, you have expansion which does work. Therefore, heat must flow into the system, regardless of the type of substance.siddharth said:That's true for an ideal gas. But for a non-ideal gas (or a general homogeneous substance), the heat absorbed will be,
[tex]dQ= C_p dT - TV \alpha dp[/tex]
where [tex]\alpha[/tex] is the coefficient of volume expansion. So, if you look at a quasi-static equilibrium process for a substance with a negative coefficient which expands on cooling in a certain temperature range (like water), the entropy change can be negative depending on the value of the integral,
[tex] \int TV \alpha dp[/tex]
The relationship between entropy and pressure at constant temperature is described by the Second Law of Thermodynamics, which states that the entropy of an isolated system will always increase over time. At constant temperature, an increase in pressure will result in an increase in entropy, as the system becomes more disordered.
Temperature plays a crucial role in determining the relationship between entropy and pressure. At constant temperature, an increase in pressure will result in an increase in entropy, while a decrease in pressure will lead to a decrease in entropy. However, at higher temperatures, the effect of pressure on entropy is more subtle.
The relationship between entropy and pressure at constant temperature is essential in thermodynamics as it helps to explain the behavior of gases and other systems. It also plays a key role in understanding phase transitions and the behavior of substances under different conditions.
No, the relationship between entropy and pressure at constant temperature cannot be reversed. The Second Law of Thermodynamics states that the entropy of an isolated system will always increase over time, meaning that the relationship between entropy and pressure cannot be reversed.
The relationship between entropy and pressure at constant temperature is closely linked to the concept of equilibrium. At equilibrium, the entropy of a system is at its maximum, and any changes to the pressure or temperature will result in a decrease in entropy and a movement away from equilibrium. This relationship allows us to predict the behavior of systems as they move towards equilibrium.