[ajax0604]

I know that if temperature is increased, the rate of reaction will increase because the reactant particles collide more frequently and with more energy so that a greater proportion of collisions are successful. However, for a decomposition reaction such as 2N₂O₅  4NO₂ + 5O₂, are the molecules of N₂O₅  colliding with each other to make the reaction occur? If not, how does temperature make the rate of decomposition increase? thank you.

[Enthalpy]

Hi,

the translation speed is only one way molecules store heat. Rotations, vibrations are other ways. Together, they can provide the energy needed for a reaction step.

N₂O₅ melts and sublimes easily, but in case you refer to the solid, maybe you don't want to call "collision" the movement of the atoms and molecules due to heat. Nevertheless, vibrations alone can bring the necessary energy to a reaction step, for instance a decomposition.

By the way, the difference between a translation speed and a vibration speed isn't that big. If the vibration mode is fully excited, the associated r.m.s. speed is the same as a gas r.m.s. translation speed, that is, the speed store kT/2 in every mode. One difference is that the deformation energy stores kT/2 r.m.s. too in a vibration, so an excited vibration stores kT while a translation stores kT/2. The other difference is that the distances a bound in a vibration, sure.

[ajax0604]

When you say "vibrations" and "rotations", are you referring to bond vibrations?

[Enthalpy]

Lmgtfy:
https://en.wikipedia.org/wiki/Molecular_vibration
http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes