Halogens exist in different physical state

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Discussion Overview

The discussion revolves around the physical states of halogens at room temperature and atmospheric pressure, specifically focusing on chlorine, bromine, and iodine. Participants explore boiling and melting points, molecular volume, and intermolecular forces, as well as the relationships between these properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant notes that chlorine is a gas, bromine is a liquid, and iodine is a solid at room temperature and atmospheric pressure, prompting questions about their boiling and melting points.
  • Another participant suggests that increasing atomic size may reduce the control of valence shell electrons, leading to more active valence electrons in iodine compared to bromine, which could affect solid formation and intermolecular forces.
  • A different participant explains that stronger intermolecular interactions result in higher boiling points, as more energy is needed to overcome these interactions.
  • There is a query about the application of the ideal gas law (PV=nRT) for calculating molecular volume, with uncertainty expressed regarding the variable 'n'.
  • One participant challenges the relevance of molecular volume to the volume of an ideal gas, indicating confusion about the estimation process for molecular volumes.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between molecular volume and intermolecular forces, as well as the application of the ideal gas law. The discussion remains unresolved regarding the specific calculations and estimations needed.

Contextual Notes

Participants have not reached consensus on the correct approach to estimating molecular volumes or the implications of boiling and melting points on intermolecular forces. There are also uncertainties regarding the application of the ideal gas law.

Who May Find This Useful

Individuals interested in physical chemistry, thermodynamics, and the properties of elements, particularly students working on related homework or projects.

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At room temperature and atmospheric pressure, the halogens exist in different physical states. Chlorine is a gas, bromine is a liquid, and iodine is a solid. What are the boiling points and melting points for these elements? Estimate the volume of the Cl2, Br2, and I2 molecules. Comment on the effect of molecular volume on intermolecular forces. Compare and contrast the intermolecular interactions of the molecules.

I think I can look for the boiling and melting points online.

For the second question, do I use PV=nRT, where P=1 atm, n=1/molar mass of the gases, and T=298K? (not sure about n)

For the 3rd and 4th question, can someone give me a hint? And does boiling and melting points relate to them in any way?

Thank you.
 
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I think increasing atomic size reduces the control of valence shell electrons by the core, thus iodine's valence electrons are more active than bromine, and so on. Solid formation involves intermolecular forces, so increased activity results in an increased rate of this kind of interaction.
 
Yeah, you can actually work out PV=nRT to find that at standard temperature and pressure 22.4L of gas corresponds to on mole of the ideal gas. You may note that some of the halogens do not exists as gases under these conditions.

With stronger intermolecular interactions will result in higher boiling points, since higher internal energy is required to achieve separation from intermolecular attractions which are due to the respective properties of each element.
 
physicsss said:
Estimate the volume of the Cl2, Br2, and I2 molecules.

For the second question, do I use PV=nRT, where P=1 atm, n=1/molar mass of the gases, and T=298K? (not sure about n)

Volume of the molecule has nothing to do with the volume of the ideal gas. No idea what kind of estimation you should made.


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