Concept explainers
(a)
The energy that must be supplied to break a single hydrogen bond.
(a)
Answer to Problem 122P
The energy that must be supplied to break a single hydrogen bond is
Explanation of Solution
The energy needed to break the bond will be the negative of the electrostatic energy of the configuration.
Write the equation for the electrostatic energy due to two point charges.
Here,
Write the equation for the electrostatic energy due to two OH charges using equation (I).
Here,
Write the equation for the electrostatic energy due to distant OH charge and the H charge using equation (I).
Here,
Write the equation for the electrostatic energy due to nearer OH charge and the H charge using equation (I).
Here,
Write the equation for the electrostatic energy due to two H charges using equation (I).
Here,
Write the equation for the total energy of the configuration.
Here,
Put equations (II), (III), (IV) and (V) in the above equation.
Substitute
Here,
Conclusion:
The value of
Substitute
The energy needed to break the hydrogen bond will be the negative of the determined electrostatic energy.
Therefore, the energy that must be supplied to break a single hydrogen bond is
(b)
The energy that must be supplied to break the hydrogen bonds in
(b)
Answer to Problem 122P
The energy that must be supplied to break the hydrogen bonds in
Explanation of Solution
Write the equation for the energy that must be supplied to break the hydrogen bonds in
Here,
Conclusion:
Each oxygen in a water molecule forms one hydrogen bond with hydrogen in another water molecule so that there will be one hydrogen bond per molecule. The value of
Substitute
The heat of vaporization of water is
Therefore, the energy that must be supplied to break the hydrogen bonds in
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Chapter 17 Solutions
Physics
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