Measurning the partial pressure of a component of a solution in equilibrium

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Discussion Overview

The discussion revolves around measuring the partial pressure of a component in a solution at equilibrium with its vapor phase. Participants explore methods to determine the mole fraction of the component in the solution, referencing relevant laws such as Raoult's Law and Henry's Law. The context includes theoretical and experimental considerations.

Discussion Character

  • Homework-related, Technical explanation, Exploratory

Main Points Raised

  • One participant suggests using Henry's Law, stating that the partial pressure equals the product of the vapor pressure in pure form and the mole fraction in the solution.
  • Another participant mentions Raoult's Law as a potential approach, contingent on knowing the amounts present in the mixture.
  • A question is raised about whether the goal is to measure or calculate the partial pressure, indicating a need for clarity in the original query.
  • It is noted that to calculate vapor pressures, measuring the mole fraction is necessary, and fractional distillation is proposed as a technique suitable for ideal mixtures like benzene and toluene.

Areas of Agreement / Disagreement

Participants express different viewpoints on the methods to be used, with some proposing Raoult's Law and others emphasizing the need for clarity in the measurement versus calculation aspect. The discussion remains unresolved regarding the best approach to measure the mole fraction.

Contextual Notes

Participants assume ideal behavior for certain mixtures, which may not hold true in all cases. The discussion does not resolve the specific apparatus or techniques needed for measuring the mole fraction.

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Homework Statement


Suppose I have two substances in a solution, each forming an equilibrium with its corresponding vapor phase, and thus having its own partial pressure. How can I measure this partial pressure of one of the components, given the pressure of each component in its pure form.

Homework Equations


The Attempt at a Solution


Using Henry's Law and assuming ideality, I know that the partial pressure of a component in the solution equals the product of the vapor pressure in the pure form multiplied by the mole fraction of the component in the solution.

So I ultimately need some way of measuring the mole fraction of the component in the solution. How can I do this? What apparatus might I need? I assume I have distillation columns, condensers, thermometers, etc. but exactly how do I proceed?

BiP
 
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Raoult's Law? (If you know their amounts present in the mixture)
 
You want to measure or to calculate? Because what you wrote doesn't sound clear.
 
I think he stated the Raoult's Law and he stated Henry's Law. So, in order to "calculate" the vapor pressures, he requires to measure the mole fraction.

For that purpose, different techniques can be used. If you are assuming ideality (good enough for benzene toluene mixture), fractional distillation will do.
 

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