4 posts • Page 1 of 1
The reaction that is least likely to occur has higher molecularity (i.e. third order reactions are less likely to occur than second order which are less likely to occur than first order). This is because two things need to happen for a reaction to occur: the molecules need to collide in the proper orientation and they need to collide with enough kinetic energy to overcome the activation energy of the reaction. The likelihood that the molecules will all collide in the proper orientation when there is more of them is much lower than when there are less of them. Therefore, lower molecularity = higher chance of occurring. This is also why third order reactions happen much slower than first order reactions.
In regards to the orientation and collision of atoms, the frequency factor, A, in the Arrhenius equation (k=Ae^-Ea/RT), represents the percentage of molecules in the reaction that actually collide to break and form new bonds (that becomes the products). Higher the A, the more likely the reaction is to go forward with a higher k value (favoring products).
Who is online
Users browsing this forum: No registered users and 1 guest