Thermodynamics: Single/Homogeneous Phase Differences

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The discussion clarifies the distinction between single phase and homogeneous phase in thermodynamics, where single phase refers to a material being entirely in one state (solid, liquid, or gas), while homogeneous indicates spatial uniformity in composition. The fundamental relation dg = vdp - sdT applies to homogeneous phases of constant composition, meaning that the mole fractions of all species remain unchanged, which is true for single-component systems. In multi-component systems, the concept of constant composition implies that the chemical potentials do not affect the free energy per mole of the mixture. The conversation also addresses the applicability of these relations in closed and open systems, emphasizing that a closed system can still utilize the equation even with multiple phases, provided the overall composition remains constant. Overall, understanding these terms is crucial for analyzing phase changes and equilibrium in thermodynamic systems.
  • #31
I tried , but cannot think of any experimental way . I guess my domain of knowledge is restricted to theoretical part .
 
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  • #32
Rahulx084 said:
I tried , but cannot think of any experimental way . I guess my domain of knowledge is restricted to theoretical part .
What you would do is prepare 2 samples of the gas with n moles total in each. The number of moles of species i in each sample would then be ##n_{i}=nx_{i}##. In one of these samples you would then add a small amount of species i so ##n_{i}=nx_{i}+\delta##. You would then compress each of these samples at temperature T from low pressure to pressure P, and measure ##nZ_{i}=\frac{PV}{RT}## at each intermediate pressure along the way. Then, from the two samples at each pressure along the way, you would evaluate ##\bar{Z_i}=\frac{\Delta nZ_{i}}{\delta}## between the two samples. Then you would use these values to evaluate the integral.
 
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