Chemistry: Heat of Sublimation and Hydrogem Bonds Problem

In summary, the conversation discusses calculating the change in enthalpy for the sublimation of water using the heats of fusion and vaporization, and estimating the portion of intermolecular forces in ice accounted for by hydrogen bonding. The first portion of the problem has been solved, with the change in enthalpy of sublimation calculated to be 46.7 kJ/mol. However, there is uncertainty about how to approach the second portion, which involves the ΔH value given in Exercise 24 and the number of hydrogen bonds formed in ice. The ΔH value in Exercise 24 is -21 kJ/mol and relates to the reaction H2O(g) + HOH(g) -> H2O --- HOH(in
  • #1
komarxian
37
0

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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  • #2
And what was the ΔH value given in the exercise 24? ΔH of what?
 
  • #3
Borek said:
And what was the ΔH value given in the exercise 24? ΔH of what?
I believe it's -21 kJ/mol
 
  • #4
ΔH of what?
 
  • #5
Borek said:
ΔH of what?
of the reaction H20 (g) + HOH (g) -> H2O --- HOH (in ice)
 
  • #6
What is ΔH of the desublimation?
 

FAQ: Chemistry: Heat of Sublimation and Hydrogem Bonds Problem

What is the heat of sublimation?

The heat of sublimation is the energy required to change a substance from a solid directly into a gas without passing through a liquid state. It is the sum of the heat of fusion (energy required to melt a solid) and the heat of vaporization (energy required to vaporize a liquid).

How is the heat of sublimation determined?

The heat of sublimation is determined experimentally by measuring the change in temperature of a substance as it sublimes. The amount of energy required to raise the temperature of the substance from its initial state to its final state is equal to the heat of sublimation.

What factors affect the heat of sublimation?

The heat of sublimation is affected by the strength of intermolecular forces between particles in a substance. The stronger the intermolecular forces, the higher the heat of sublimation will be. Other factors that may affect the heat of sublimation include temperature, pressure, and the physical properties of the substance.

What are hydrogen bonds and how do they affect the heat of sublimation?

Hydrogen bonds are strong intermolecular forces that occur between a hydrogen atom bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) and another electronegative atom. These bonds are responsible for many of the unique properties of water, such as its high boiling point and surface tension. In substances with hydrogen bonds, the heat of sublimation is typically higher due to the strong intermolecular forces present.

How is the heat of sublimation used in everyday life?

The heat of sublimation is used in many everyday applications, such as freeze-drying food, making instant coffee or tea, and purifying substances through sublimation. It is also an important concept in industries such as pharmaceuticals, where the stability and purity of a substance can be affected by its heat of sublimation. Understanding the heat of sublimation is also crucial in fields such as meteorology and climate science, where the sublimation of ice into water vapor plays a role in temperature and humidity changes in the atmosphere.

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