Chemistry: Heat of Sublimation and Hydrogem Bonds Problem

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Discussion Overview

The discussion revolves around calculating the change in enthalpy for the sublimation of water and estimating the contribution of hydrogen bonding to the intermolecular forces in ice. It includes aspects of thermodynamics and intermolecular forces.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant has calculated the change in enthalpy of sublimation as 46.7 kJ/mol but is uncertain about how to approach the estimation of intermolecular forces related to hydrogen bonding.
  • Several participants inquire about the ΔH value referenced in Exercise 24, seeking clarification on its specific context and value.
  • One participant suggests that the ΔH value might be -21 kJ/mol, although this is not confirmed.
  • There are multiple requests for clarification regarding the ΔH of the reaction involving water in different states.
  • Another participant asks about the ΔH of desublimation, indicating a potential area of confusion or further inquiry.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the ΔH value from Exercise 24, and there is uncertainty regarding the specifics of the enthalpy changes involved in the reactions discussed.

Contextual Notes

The discussion lacks clarity on the definitions and values of ΔH referenced, and there are unresolved questions regarding the calculations and assumptions related to intermolecular forces and hydrogen bonding.

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Homework Statement


Using the heats of fusion and vaporization for water, calculate the change in enthalpy for the sublimation of water:

H2O(s) --> H2O(g

Using the delta H value given in Exercise 24 and the number of hydrogen bonds formed to each water molecule, estimate what portion of the intermolecular forces in ice can be accounted for by hydrogen bonding.

Homework Equations

The Attempt at a Solution


I have already figured out the first portion of the problem, finding the change in enthalpy of sublimation ( I got 46.7 kJ/mol ), but I'm really not sure as to how to attack the portion of IMF and hydrogen bonding. Any help is greatly appreciated.
 
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And what was the ΔH value given in the exercise 24? ΔH of what?
 
Borek said:
And what was the ΔH value given in the exercise 24? ΔH of what?
I believe it's -21 kJ/mol
 
ΔH of what?
 
Borek said:
ΔH of what?
of the reaction H20 (g) + HOH (g) -> H2O --- HOH (in ice)
 
What is ΔH of the desublimation?
 

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