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16 Ιαν 2023 · Entropy changes are fairly easy to calculate so long as one knows initial and final state. For example, if the initial and final volume are the same, the entropy can be calculated by assuming a reversible, isochoric pathway and determining an expression for \(\frac{dq}{T}\).
- 19.2: Entropy and the Second Law of Thermodynamics
Changes in entropy (ΔS), together with changes in enthalpy...
- 10.5: Entropy and the Second Law of Thermodynamics
The formula for the entropy change in the surroundings is...
- 4.7: Entropy - Physics LibreTexts
Calculate the change of entropy for some simple processes....
- 13.4: The Second Law and Entropy - Physics LibreTexts
The total change in the entropy of the closed system formed...
- 15.6: Entropy and the Second Law of Thermodynamics- Disorder and the ...
Calculate the total change in entropy if 4000 J of heat...
- 19.2: Entropy and the Second Law of Thermodynamics
Changes in entropy (ΔS), together with changes in enthalpy (ΔH), enable us to predict in which direction a chemical or physical change will occur spontaneously. Before discussing how to do so, however, we must understand the difference between a reversible process and an irreversible one.
The equation for the change in entropy, Δ S Δ S, is Δ S = Q T , Δ S = Q T , where Q is the heat that transfers energy during a process, and T is the absolute temperature at which the process takes place.
The formula for the entropy change in the surroundings is \(\Delta S_{surr}=\Delta H_{sys}/T\). If this equation is replaced in the previous formula, and the equation is then multiplied by T and by -1 it results in the following formula.
Calculate the change of entropy for some simple processes. The second law of thermodynamics is best expressed in terms of a change in the thermodynamic variable known as entropy, which is represented by the symbol S. Entropy, like internal energy, is a state function.
The total change in the entropy of the closed system formed by the two objects will then be. dStotal = dS1 + dS2 = dQ1 T1 + dQ2 T2. and the requirement that this cannot be negative (that is, Stotal must not decrease) is just the same as Equation (13.4.2), in differential form.
Calculate the total change in entropy if 4000 J of heat transfer occurs from a hot reservoir at \(T_h = 600 \, K \, (327^oC) \) to a cold reservoir at \(T_c = 250 \, K \, (-23^oC)\), assuming there is no temperature change in either reservoir.
