# Computation of Liquid/Vapor Result during a Volume Expansion

• Chemistry
• Bcavender
In summary: No, that is not necessary. However, enthalpy data can be helpful in helping to understand the thermodynamic principles at play.No, that is not necessary. However, enthalpy data can be helpful in helping to understand the thermodynamic principles at play.
Bcavender
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

You have not fully constrained your inquiry; what other information do you need to furnish for us to answer your question?

Chestermiller
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

Bystander
You need any enthalpy/latent heat data for this ?

## 1. What is the purpose of computing liquid/vapor result during a volume expansion?

The purpose of computing liquid/vapor result during a volume expansion is to analyze and understand the thermodynamic behavior of a substance as it changes from a liquid to a vapor state during an expansion process. This information is important for various industries, such as in the design of power plants and refrigeration systems.

## 2. How is the liquid/vapor result computed during a volume expansion?

The liquid/vapor result is computed by using thermodynamic equations and data, such as the substance's specific heat, enthalpy, and entropy, to model the behavior of the substance as it undergoes a volume expansion. This can be done using mathematical software or through manual calculations.

## 3. What factors can affect the liquid/vapor result during a volume expansion?

Several factors can affect the liquid/vapor result during a volume expansion, including the initial and final volume of the substance, the pressure and temperature at which the expansion occurs, and the specific properties of the substance, such as its molecular weight and heat capacity.

## 4. Why is it important to accurately compute the liquid/vapor result during a volume expansion?

Accurately computing the liquid/vapor result during a volume expansion is important because it allows for the prediction and optimization of various thermodynamic processes, which can lead to more efficient and cost-effective systems. It also helps to ensure the safety and reliability of these systems.

## 5. What are some potential applications of the computation of liquid/vapor result during a volume expansion?

The computation of liquid/vapor result during a volume expansion has many practical applications, including in the design and analysis of power plants, refrigeration and air conditioning systems, and chemical processes. It can also be used in the development of new materials and in the study of phase transitions in various substances.

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