Computation of Liquid/Vapor Result during a Volume Expansion

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SUMMARY

The discussion focuses on methodologies for calculating the phase change of water during volume expansion, specifically transitioning from liquid to vapor. Bruce seeks to extend beyond Boyle's Law to understand the necessary parameters for this calculation, including density, molar mass, and total mass. Key values provided include a density of 0.99802 g/cm3, a starting volume of 500 cm3, and a molar mass of 18.01528 g/mol, resulting in approximately 27.7 moles of water. Participants suggest that understanding the vapor pressure and enthalpy data is crucial for accurately determining the vapor production during expansion.

PREREQUISITES
  • Understanding of phase change principles in thermodynamics
  • Familiarity with Boyle's Law and its limitations
  • Knowledge of molar mass and density calculations
  • Basic concepts of vapor pressure and enthalpy
NEXT STEPS
  • Research "water phase change graphs" for visual understanding of phase transitions
  • Study "vapor pressure calculations" to determine equilibrium points
  • Learn about "enthalpy and latent heat" to understand energy changes during phase transitions
  • Explore "ideal gas law applications" in relation to vapor production
USEFUL FOR

Engineers, chemists, and students involved in thermodynamics, particularly those working with phase changes in fluids and gas-liquid equilibria.

Bcavender
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Homework Statement
PROBLEM:

An expandable container, with a starting volume of 0.5 liter is filed completely with a liquid having a vapor pressure of 2.4 kPa.

The internal starting pressure is 1 atm and temperature of 20 degrees C.

The container expands to a new volume of 30 liters.

What are:

(1) The final volume of liquid at equilibrium?

(2) The internal pressure at equilibrium?

(3) The temperature of the gas?

(4) The temperature of the liquid?
Relevant Equations
I am searching for the appropriate methodology/equation(s) to step beyond Boyle's Law to account for the phase change and solve this problem.

All suggestions/guidance is greatly appreciated!
Bruce
I am searching for the appropriate methodology/equation(s) to step beyond Boyle's Law to account for the phase change and solve this problem.

All suggestions/guidance is greatly appreciated!
Bruce
 
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You have not fully constrained your inquiry; what other information do you need to furnish for us to answer your question?
 
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Bystander said:
You have not fully constrained your inquiry; what other information do you need to furnish for us to answer your question?

Good afternoon Bystander,

I am not sure what further constraints you speak of. My chemistry background is limited as I do mostly electrical/electronic work and I am exploring for a methodology for my super.

Boyles Law may come into play some way partially or not, but I lack the understanding of how to approach a formulation of the equation(s) for the vapor production and liquid volume reduction as the volume increases and pressure drops.

How can I further determine the parameters that are necessary to "fully constrain" the question?

Thanks!
Bruce
 
Bcavender said:
parameters that are necessary to "fully constrain" the question?
Number of moles, or equivalent information (density plus molecular weight plus total volume/mass) for starters; get you going?
 
Bystander said:
Number of moles, or equivalent information (density plus molecular weight plus total volume/mass) for starters; get you going?

Density = 0.99802 g/cm^3
Starting Volume = 500 cm^3 (all liquid)

Molar mass = 18.01528 g/mol
Total Mass = 499.01/18.01528 = 27.7 mol

Can you suggest a reference where I can find the methodology to understand the mechanics and computation of how much mass becomes vapor after expansion from 0.5L to 30L and other conditions?
 

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Bystander said:

OK, let's see if this is progress.

For a given amount of volume expansion, a new liquid/gas equilibrium point would be where the amount of vapor moles produced would allow the pressure in the gas volume to grow to equal the vapor pressure of the remaining liquid given compensation for by the phase change temperature drop in the gas molecules as well as the liquid volume reduction due to vaporization.

Would this statements be correct?Bruce
 
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You need any enthalpy/latent heat data for this ?
 

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