Physical Chemistry water vapor/phases present question?

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Discussion Overview

The discussion revolves around a physical chemistry problem involving the phases of water (liquid and gas) in a container, specifically addressing the conditions under which each phase is present, as well as calculations related to vapor pressure and volume. The scope includes theoretical and mathematical reasoning related to phase behavior and vapor pressure calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant asserts that both gas and liquid phases are present in the container.
  • Another participant calculates the volume at which only the gas phase would be present using the formula RT/(nP), resulting in a volume of 594 L.
  • A different calculation for the volume at which only the liquid phase would be present yields 0.024 L, based on the number of moles of water.
  • One participant questions the use of the formula RT/(nP), suggesting it is incorrect, and expresses confusion over the calculations presented for the liquid phase volume.
  • Clarifications are made regarding the conversion of pressure units from Torr to Pa and then to bar, indicating a preference for the unit used in the textbook.
  • There is a mention of a specific volume of gas (0.018 Vm) referenced from a textbook, which is used in the calculations.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the calculations or the formula used. There are competing views regarding the validity of the approach taken for determining the volumes associated with each phase of water.

Contextual Notes

Participants express confusion over the application of certain formulas and the assumptions made in the calculations, particularly regarding the phase behavior of water and the conditions for having only one phase present.

qnzbabi91
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23.7 g of water is in a container of 23.7 L at 298.15 . The vapor pressure of water at this temperature is 23.76 Torr.
A) What phases are present?
B) At what volume would only the gas phase be present?
C) At what volume would only the liquid phase be present?



A) I know that only the gas and liquid are present.

B) I used RT/(nP) to find the volume and got (0.08314*298)/(23.7/18 * 23.76 * 133.322/10^5) = 594 L

C) I used 0.018* 23.7/18.02 = 0.024 L

Thanks for any help! =]
 
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qnzbabi91 said:
23.76 * 133.322/10^5

C) I used 0.018* 23.7/18.02 = 0.024 L

Please elaborate.
 
Okay, so 23.76 is the P in torr so I converted to Pa by multiplying by 133.322 and then I divided by 10^5 to convert Pa to bar. In my textbook the authors used bar so I thought I should as well.

For the second part, I found the 0.018 Vm of gas in my physical chemistry textbook, so I just multiplied it by the number of moles in question.

I am semi-confused.
 
\frac{RT}{nP} is an incorrect formula.

And I have no idea what you did in C. However, the only way to have no gas is to have whole volume occupied by liquid.
 

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