Estimating Vapor Pressure of Mercury at 25°C Using Appendix D Data

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Discussion Overview

The discussion revolves around estimating the vapor pressure of mercury at 25°C using data from Appendix D of a textbook. Participants explore the application of thermodynamic principles and equations relevant to vapor pressure calculations.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant expresses uncertainty about how to start estimating the vapor pressure, suggesting that vapor pressure might be found when ΔG=0.
  • Another participant recommends using the Clausius-Clapeyron equation and mentions the boiling point of mercury as a useful reference for integration.
  • A participant confirms they have not used the Clausius-Clapeyron equation before but has previously determined the boiling point of mercury.
  • A later reply provides the specific form of the Clausius-Clapeyron equation, noting that it assumes the latent heat of vaporization is constant, while also suggesting the possibility of integrating if an expression for ΔH_{vap} as a function of temperature is available.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the approach to take, with some uncertainty expressed regarding the use of the Clausius-Clapeyron equation and the assumptions involved.

Contextual Notes

There are limitations regarding the assumptions made about the latent heat of vaporization and the dependence on specific temperature data. The discussion does not resolve how to handle these assumptions in the context of the calculations.

annastewert
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Homework Statement


Estimate the vapor pressure of mercury at 25 ∘C (use data from Appendix D from the textbook).

Homework Equations


Using the appendix I can find ΔG, ΔH, and ΔS.

The Attempt at a Solution


I have no idea where to start. I think that maybe vapor pressure would be found when ΔG=0, but I'm not certian of that. How could I use this information to find the vapor pressure?
 
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Given your data, you need to use the Clausius-Clapeyron equation and integrate it. You may use the boiling point of mercury in order to find the constant of integration.

Have you ever used the equation before?
 
I have not used the equation before but the previous question was to find the boiling point so I do have that
 
This is the equation you need to use. It assumes the latent heat of vaporization is constant, however, it would still be possible to integrate the equation if you have an expression for \Delta H_{vap} as a function of temperature.
\frac{d \ln P}{dT} = \frac{\Delta H_{vap}}{RT^2}
And as I previously said, you may use the boiling point of mercury to find the constant of integration.
 

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