Help with Thermo Problem, vaporization of water into evacuated vessel

In summary, 1 mole of water vapor at 1 atm and 100C will result in 1 mole of water in the final state.
  • #1
ThermoStudent
2
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one mole of liquid water (100 deg C, vapor pressure = 1 atm) in a container is introduced into an evacuated vessel maintained at 100 deg C and allowed to evaporated. The volume of the vessel is such that the final pressure of the gaseous water is 0.1 atm. Given the (normal) latent heat of 9,730 cal per mole at 100 deg C, and assuming the vapor is ideal, calculate q, w, delta H, delta G and delta S for this process. [/b]

So I know that I need to find a reversible path for this problem, but I don't really know where to start.
I started by using the latent heat to find q using the formula L = Q/m
But other than that I have no idea where to go with this. I would very much appreciate any help on this problem.
 
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  • #2


Ask yourself the following question: Is it possible for any liquid water to be remaining in the vessel if the final temperature is 100C and the final pressure is 0.1 atm? You know you have 1 mole of water, so this should give you enough information to get the volume of the vessel. Is the volume of the vessel really needed to determine the solution to the various parts of your problem?
 
  • #3


Yeah, I can find the final volume of the vessel by using the ideal gas law, but I'm having a problem deciding a reversible path for this process.
 
  • #4


What if there is no reversible path? The liquid water evaporates into the evacuated vessel. Unless the latent heat of vaporization is removed from the water vapor, it is not going to condense back into a liquid. With a final pressure of 0.1 atm and a temp of 100C, I would expect that very little liquid could exist.
 
  • #5


The initial and final states are:

Initial: 1 mole of Liquid Water at 1 atm. and 100C

Final: 1 mole of water vapor at 0.1 atm. and 100C

You need to figure out how to go from the initial state to the final state reversibly - not necessarily in the vessel described in the problem.

Consider an Intermediate State: 1 mole of water vapor at 1 atm and 100C.

How do you go reversibly from the initial state to the intermediate state? How much reversible heat is required? What is delta H. What is delta S. What is delta G?

How do you go reversibly from the intermediate state to the final state? How much reversible heat is required? What is delta S? What is delta G?

chet
 

FAQ: Help with Thermo Problem, vaporization of water into evacuated vessel

What is the process of vaporization of water into an evacuated vessel?

The process of vaporization of water into an evacuated vessel involves heating water until it reaches its boiling point, which is 100 degrees Celsius or 212 degrees Fahrenheit. At this point, the water molecules gain enough energy to break free from their liquid state and become a gas. The gas molecules then fill the evacuated vessel, creating a vapor-filled environment.

What is the purpose of an evacuated vessel in the process of vaporization of water?

The purpose of an evacuated vessel in the process of vaporization of water is to create a low-pressure environment. This allows water to boil at a lower temperature, which can be useful for certain experiments or processes. It also prevents any outside air or contaminants from entering the vessel, ensuring a pure vapor environment.

How does the temperature and pressure affect the vaporization of water into an evacuated vessel?

The temperature and pressure are closely related in the process of vaporization of water into an evacuated vessel. As the temperature increases, the pressure inside the vessel also increases. This is because the gas molecules have more energy and are moving faster, creating a higher pressure. Similarly, as the pressure decreases, the temperature also decreases, making it easier for the water to vaporize.

What factors can affect the rate of vaporization of water into an evacuated vessel?

The rate of vaporization of water into an evacuated vessel can be affected by several factors. These include the temperature and pressure of the environment, the surface area of the water, and the presence of impurities in the water. The type of vessel used and the presence of any insulation can also impact the rate of vaporization.

What are some practical applications of the process of vaporization of water into an evacuated vessel?

The process of vaporization of water into an evacuated vessel has several practical applications. It can be used in distillation processes to separate liquids based on their boiling points. It is also used in various industries, such as food manufacturing, to remove excess moisture from products. Additionally, it is used in laboratory experiments to create controlled environments for testing and research purposes.

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