What are some questions about thermodynamics and their potential answers?

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Discussion Overview

The discussion revolves around a series of questions related to thermodynamics, specifically focusing on the properties of water at a boiling point of 372.78 K and a pressure of 1 bar. Participants explore calculations of molar volumes, distances between water molecules, and the application of various equations of state, including the ideal gas law, virial equation, and van der Waals' equation.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related
  • Debate/contested

Main Points Raised

  • Participants inquire about the molar volumes of liquid and gaseous water at specified conditions, with calculations provided by one participant using Charles' law.
  • Questions are raised regarding the average distance between nearest-neighbor water molecules based on the assumption of exclusion volume.
  • There is a request to calculate the molar volume of gaseous water using the ideal gas equation and to determine the error compared to previous calculations.
  • Participants discuss the virial coefficient for water and its implications for calculating molar volume using the virial equation.
  • One participant mentions the van der Waals' equation and its parameters for water, seeking to compute molar volume and associated errors.
  • There is a request for comments on the results from previous calculations and speculation on the accuracy of these results at lower pressures.
  • Some participants express confusion about the intent behind the questions and the lack of detailed explanations accompanying the answers provided.

Areas of Agreement / Disagreement

There is no consensus on the correct answers to the questions posed, as participants express uncertainty and seek clarification on various aspects of the calculations and underlying principles.

Contextual Notes

Participants note the potential for errors in calculations and the dependence on assumptions made regarding the properties of water. There is also mention of the molar mass of water being the same for both liquid and gaseous states, which may influence the calculations.

Who May Find This Useful

This discussion may be of interest to students and professionals in chemistry and thermodynamics, particularly those looking to understand the properties of water and the application of different equations of state in practical scenarios.

WMDhamnekar
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Hello,
Here are the questions with unknown answers. (These chemistry questions are other math topics.)
1) At 1 bar, the boiling point of water is 372.78 K. At this temperature and pressure, the density of liquid water is $958.66 kg/m^3$ and that of gaseous water is $0.59021 kg/m^3.$ What are the molar volumes. in $m^3 mol^{-1}$ of liquid and gaseous water at this temperature and pressure? in Liters/mol?

2) Refer to the answer to 1) question. Assuming that a water molecule excludes the other water molecules from a cubic region centered on itself, estimate the average distance between nearest-neighbor water molecules in the liquid and in the gas.

3)Calculate the molar volume and gaseous water at 1 bar and 372.78 K from ideal gas equation. What is the error, expressed as a percentage of the value, you calculated in question 1).

4) At 372.78 K, the virial coefficient B* for water is $-1.487 × 10^{-7} Pa^{-1}$. Calculate the molar volume of gaseous water at 1 bar and 372.78 K from the virial equation: $Z=P\overline{V}/RT= 1+B^*P.$ What is the error, expressed as a percentage of the value, you computed in question 1).

5) Compute the molar volume of gaseous water at 1 bar and 372.78 K from van der Waals' equation. The van der Waals' parameters for water are $a=5.537 bar L^2 mol^{-1}$ and $b=0.0305 L mol^{-1}$. What is the error, expressed as the percentage of the value, you computed in question 1)?

6)What are your comments on the results in questions 3,4 and 5? At this temperature, would you expect the accuracy to increase or decrease at lower pressure?
 
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Dhamnekar Winod said:
Hello,
Here are the questions with unknown answers. (These chemistry questions are other math topics.)
1) At 1 bar, the boiling point of water is 372.78 K. At this temperature and pressure, the density of liquid water is $958.66 kg/m^3$ and that of gaseous water is $0.59021 kg/m^3.$ What are the molar volumes. in $m^3 mol^{-1}$ of liquid and gaseous water at this temperature and pressure? in Liters/mol?

2) Refer to the answer to 1) question. Assuming that a water molecule excludes the other water molecules from a cubic region centered on itself, estimate the average distance between nearest-neighbor water molecules in the liquid and in the gas.

3)Calculate the molar volume and gaseous water at 1 bar and 372.78 K from ideal gas equation. What is the error, expressed as a percentage of the value, you calculated in question 1).

4) At 372.78 K, the virial coefficient B* for water is $-1.487 × 10^{-7} Pa^{-1}$. Calculate the molar volume of gaseous water at 1 bar and 372.78 K from the virial equation: $Z=P\overline{V}/RT= 1+B^*P.$ What is the error, expressed as a percentage of the value, you computed in question 1).

5) Compute the molar volume of gaseous water at 1 bar and 372.78 K from van der Waals' equation. The van der Waals' parameters for water are $a=5.537 bar L^2 mol^{-1}$ and $b=0.0305 L mol^{-1}$. What is the error, expressed as the percentage of the value, you computed in question 1)?

6)What are your comments on the results in questions 3,4 and 5? At this temperature, would you expect the accuracy to increase or decrease at lower pressure?

Hello,
Answer to question 1)

Molar volume of liquid water is $0.00001879m^3/mol$

Molar volume of gaseous water is $0.030589 m^3/mol $ using charles' law for temperature-volume relationship.
 
Hey Dhamnekar Winod,
What is it that you really want to know?
After all, so far you have merely posted a set of problem statements. And you followed up with what appears to be textbook answers without explanation.
Either way, there are plenty of those in various textbooks.
Is there something that you are stuck on? If so, what is it?
 
Klaas van Aarsen said:
Hey Dhamnekar Winod,
What is it that you really want to know?
After all, so far you have merely posted a set of problem statements. And you followed up with what appears to be textbook answers without explanation.
Either way, there are plenty of those in various textbooks.
Is there something that you are stuck on? If so, what is it?
Hi,
I don't know the correct answers to all of these question for verifications. I also don't know how to answer question 2), 5). As question 5) is still unsolved, I can't go further to consider answering question 6).

So, i am studying answers given by learned science professors to similar types of questions. It took much time to answer 1), because i was not knowing that molar mass of gaseous water and liquid water is one and the same, that is 18.02g/mol.
 

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