Solving Intermolecular Bonding Exercises: B2H6, CH4, NH3 & H2S

In summary, the conversation discusses the concepts of intermolecular forces and electronegativity in relation to activation energy and hydrogen bonding. The question posed is which of the given combustion reactions will have the lowest energy of activation, and which hydrogen bond will be strongest. The answer lies in considering the strength of intermolecular forces and the electronegativity of the atoms involved. In the end, the conversation concludes with a request for clarification and a summary of the main points discussed.
  • #1
broegger
257
0
Hi. I need help with (part of) this exercise:

c) By considering the differences in bonding determine which of the combustion reactions (in part a) I have written combustion reactions for the following hydrides: B2H6, CH4, NH3 and H2S) must be expected to have the lowest energy of activation.

f) Hydrogen bonding is the strongest intermolecular interaction, and it is of enormous importance in chemistry. Two important hydrogen bondings is O-H---O and N-H---H. Which of these two hydrogen bonds must be expected to be strongest (explain)?

I'm lost again... Any hints?
 
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  • #2
You know the rules - we need to some some thought process from you first.
 
  • #3
c) Think intermolecular forces.
f) Think electronegativity.
 
  • #4
end3r7 said:
c) Think intermolecular forces.
f) Think electronegativity.

c) Still in the dark. Can't relate these things to the activation energy... sorry.

f) Oxygen is more electronegative than nitrogen, so the OH-molecule has a greater dipole strength than the NH-molecule and therefore the hydrogen bond is stronger in the former case (O-H---O). Right?

Thanks for helping.
 
  • #5
c) What is it that is keeping the atoms in the molecules from just breaking loose? What is needed to break bonds between atoms?
 

Related to Solving Intermolecular Bonding Exercises: B2H6, CH4, NH3 & H2S

1. What is intermolecular bonding?

Intermolecular bonding is the attraction between molecules or particles that hold them together. It is different from intramolecular bonding, which refers to the bonds within a molecule.

2. How do you solve exercises on intermolecular bonding?

To solve exercises on intermolecular bonding, you need to first identify the molecules involved and their structural formula. Then, determine the type of intermolecular bonding present (such as hydrogen bonding, dipole-dipole interactions, or London dispersion forces) and draw the appropriate intermolecular forces diagram. Finally, compare the strength of these intermolecular forces to predict the relative boiling points, melting points, and solubility of the molecules.

3. What are the intermolecular bonding properties of B2H6, CH4, NH3, and H2S?

B2H6 (diborane) has covalent bonds and weak London dispersion forces, CH4 (methane) has only London dispersion forces, NH3 (ammonia) has hydrogen bonding, and H2S (hydrogen sulfide) has dipole-dipole interactions and London dispersion forces.

4. Why is NH3 able to form hydrogen bonds?

NH3 has a polar structure due to the electronegativity difference between nitrogen and hydrogen atoms. The lone pair of electrons on the nitrogen atom creates a strong dipole-dipole interaction with hydrogen atoms of other NH3 molecules, resulting in hydrogen bonding.

5. How does intermolecular bonding affect the physical properties of a substance?

The strength and type of intermolecular bonding affects the physical properties of a substance such as boiling point, melting point, and solubility. Stronger intermolecular forces result in higher boiling and melting points, as well as increased solubility in polar solvents. Substances with weaker intermolecular forces will have lower boiling and melting points and may not dissolve in polar solvents.

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