bond enthalpies

[Ekayana Sethi 2K]

In lecture Professor Lavelle said something about converting all products and reactants into gas form to use bond enthalpies. I did not understand what he meant. How do we convert something into gas?

[Peri Bingham 1G]

To convert the bond enthalpies into a gas, you must add the enthalpy of vaporization (if going from liquid to gas) or the enthalpy of sublimation (if going from solid to gas).

[Clarisse Wikstrom 1H]

In addition, you must do this because it would take much more energy to break the bonds for liquid or solid compounds... the bond enthalpies would extremely high.

[lindsay lathrop 2C]

We have to consider it in a gas form because bond enthalpy is the dissociation of a species in its gas phase. Therefore we have to use the vaporization or sublimation values because that is how liquids and solids become gases respectively