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

[broegger]

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?

 

[Gokul43201]

You know the rules - we need to some some thought process from you first.

 

[end3r7]

c) Think intermolecular forces.
f) Think electronegativity.

 

[broegger]

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.

 

[Mattara]

c) What is it that is keeping the atoms in the molecules from just breaking loose? What is needed to break bonds between atoms?