Estimate the latent heat of water with Van der Waals

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SUMMARY

The forum discussion focuses on estimating the latent heat of vaporization of water and nitrogen using the Van der Waals model. The key equations referenced include the entropy equation \( S = nR\left[ \ln\left(\frac{(V-nb)T^{3/2}}{n\Phi}\right)+\frac{5}{2} \right] \) and the relationship \( \Delta Q = T\Delta S = L \). The initial prediction suggests that the Van der Waals model will inaccurately approximate the latent heat of vaporization for water, leading to the assumption that \( \Delta S \) could be zero, resulting in zero latent heat.

PREREQUISITES
  • Understanding of the Van der Waals equation of state
  • Familiarity with thermodynamic concepts such as latent heat and entropy
  • Knowledge of the relationship between temperature, entropy, and heat transfer
  • Basic proficiency in manipulating equations in thermodynamics
NEXT STEPS
  • Research the Van der Waals equation and its applications in thermodynamics
  • Study the concept of latent heat and its significance in phase transitions
  • Explore the derivation and implications of the entropy equation in thermodynamic systems
  • Investigate alternative models for estimating latent heat, such as the Clausius-Clapeyron equation
USEFUL FOR

This discussion is beneficial for students and professionals in thermodynamics, particularly those studying phase transitions and the application of the Van der Waals model in estimating latent heat.

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Homework Statement



Try to estimate the latent heat of vaporization of water and nitrogen using the Van der Waals model. What happens?

Homework Equations



$$\Delta Q = T\Delta S=L$$
$$S=nR\left[ \ln\left(\frac{(V-nb)T^{3/2}}{n\Phi}\right)+\frac{5}{2} \right]$$

The Attempt at a Solution



I predict the latent heat of vaporization of water will be wrongly approximated by the Van der Waals model. By looking at the equation for entropy I think the ##\Delta S## is going to be zero, so the latent heat would be zero also. But I am not sure if I am looking at the problem in the wrong way.
 
Hi me,
I had already replied with : why do you think ##\Delta S = 0 ## ?

didn't come across ?
 

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