How Does Vapour Pressure Change at Dew Point for Benzene-Toluene Mixtures?

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SUMMARY

The discussion focuses on the vapor pressure behavior of equimolar benzene and toluene mixtures at 20°C, where the vapor pressures are 9.866 kPa for benzene and 2.933 kPa for toluene. The application of Dalton's and Raoult's Laws is essential for calculating the vapor pressure when only a few droplets of liquid remain. As the solution is boiled by reducing external pressure, the remaining species will predominantly be the one with the higher vapor pressure, which is benzene in this case.

PREREQUISITES
  • Understanding of Dalton's Law of Partial Pressures
  • Familiarity with Raoult's Law
  • Knowledge of vapor pressure concepts
  • Basic thermodynamics principles
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  • Study the application of Dalton's Law in multi-component systems
  • Research Raoult's Law for non-ideal solutions
  • Explore the thermodynamic properties of benzene and toluene
  • Learn about phase diagrams and their relevance to vapor-liquid equilibrium
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cruckshank
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THERE IS NO TEMPLATE BECAUSE GHIS HOMEWORK WAS PLACED IN AN INCORRECT FORUM

Equimolar benzene and and toluene form essentially ideal solutions. At 20degC the vapour of benzene and toluene are 9.866kPa and 2.933kPa respectively. The solution is boiled by reducing the external pressure below the vapour pressure.

What is the vapour pressure when only a few droplets of liquid remain? Assume still at 20degC.

I know I need to use Dalton's/Raoult's Law, but can't work out how to start really. Help would be appreciated, thanks.
 
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From your problem statement info, what are the vapor pressures of pure toluene and pure benzene at 20 C?
 
When most of the liquid has boiled away, which of the two species remains?
 

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