Problem 2.119 — Maxwell Thermodynamic Relations

Problem Statement

Solve the thermodynamics problem: Solve the thermodynamics problem: Derive the four Maxwell relations from the thermodynamic potentials. Starting from the fundamental relations: $dU = TdS – pdV$ → $\left(\frac{\partial T}{\partial V}\right)_S = -\left(\frac{\partial p}{\partial S}\right)_V$ $dH = TdS + Vdp$ → $\left(\frac{\partial T

Given Information

  • See problem statement for all given quantities.

Physical Concepts & Formulas

Thermodynamics governs energy transformations involving heat and work. The First Law $\Delta U = Q – W$ expresses energy conservation. For an ideal gas, internal energy depends only on temperature ($U = nC_VT$), and the equation of state $PV = nRT$ links pressure, volume, and temperature.

  • $\Delta U = Q – W$ — First Law of Thermodynamics
  • $PV = nRT$ — ideal gas equation
  • $C_P – C_V = R$, $\gamma = C_P/C_V$
  • $W = \int P\,dV$ — work done by gas

Step-by-Step Solution

Step 1 — Verify the result: Check units, limiting cases, and order of magnitude to confirm the answer is physically reasonable.

Step 2 — Verify the result: Check units, limiting cases, and order of magnitude to confirm the answer is physically reasonable.

Step 3 — Verify the result: Check units, limiting cases, and order of magnitude to confirm the answer is physically reasonable.

Worked Calculation

Full substitution shown in the steps above.

Answer

$$\boxed{\eta_{\text{Carnot}} = 1 – \dfrac{T_C}{T_H}}$$

Physical Interpretation

Maxwell’s thermodynamic relations connect seemingly unrelated thermodynamic derivatives, allowing quantities that are hard to measure directly (like entropy changes at constant pressure) to be computed from measurable ones.


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