Question

Make a generalization about the energy required to separate molecules (as in boiling) compared to the energy required to break covalent bonds.

Answer 1

Assume 1 mol of H2O:

Enthalpy of vaporization = 40.660 kJ/mol

Enthalpy Required to break H-O-H bonds = 2x(O-H) = 2x(463) kJ/mol = 926 kJ/mol

clearly

we require much more energy to break H2O + H2O interacitons to boil water

than H-O-H bonds to form H2 and O2 gases form H2O

This is present due to the electron configuration of each specie.

Note that H-O is bonded by ELECTRONIC interactions which form the INTRAMOLECULAR forces

For H2O there are INTERMOLECULAR forces, i.e. note that these are "sueprficial" therefore easier to break (easier to boil than to form chemical H2 and O2)