Internal Energy & Ideal Gas: Is dH=Cp dT Always?

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SUMMARY

For an ideal gas, the change in internal energy (dU) is directly related to temperature changes, expressed as dU = CvdT, where Cv is the specific heat at constant volume. The discussion confirms that the change in enthalpy (dH) can also be expressed as dH = Cp dT, where Cp is the specific heat at constant pressure, even when pressure is not constant. This relationship holds true due to the equation dH = dU + d(pV), which simplifies to dH = (Cv + R)dT for ideal gases.

PREREQUISITES
  • Understanding of ideal gas laws
  • Familiarity with thermodynamic concepts such as internal energy and enthalpy
  • Knowledge of specific heats (Cv and Cp)
  • Basic calculus for interpreting differential equations
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  • Study the derivation of the ideal gas law and its implications
  • Learn about the differences between Cv and Cp in thermodynamics
  • Explore the concept of enthalpy in non-ideal gases
  • Investigate the applications of dH = Cp dT in real-world thermodynamic processes
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kelvin490
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For an ideal gas, the internal energy is a function only of temperature, so that dU = CvdT can always be applied. I am not sure whether dH=CP dT is also always true even the pressure is not constant.
 
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kelvin490 said:
For an ideal gas, the internal energy is a function only of temperature, so that dU = CvdT can always be applied. I am not sure whether dH=CP dT is also always true even the pressure is not constant.
For an ideal gas, it is. dH = dU + d(pV) = dU + RdT=(Cv+R)dT

Chet
 
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