Bond Enthalpy at Different Temperatures

[MathewsMD]

I was recently learning average bond enthalpies and was wondering if it varies at different temperatures. I know that in different molecular configurations, bond strength is affected by the arrangement of the atoms, but at higher temperatures, there is higher vibrational energy, right? So, if we were to compare the C-H bonds in methane at 273.15 K vs 300 K, would we find significant or trivial difference in their respective bond enthalpies? Would the reasoning be because of the additional vibrational energy or is there another factor in play (e.g. increased Van der Waals forces allow for easier breaking of bonds)?

 

[jbsteele]

It is true that at higher temperatures, there is increased vibrational energy, and this can affect the bond enthalpy. However, the difference in bond enthalpies between 273.15 K and 300 K will be very small. The main factor in the difference in bond enthalpy is the arrangement of the atoms, not the additional vibrational energy, as the increase in temperature is too small to cause a significant change in the bond strength. The additional vibrational energy may contribute to some minor changes in bond enthalpies, but these are unlikely to be significant. Van der Waals forces also have minimal influence on bond enthalpy, as these forces are generally much weaker than covalent bonds.