Is a Collision Between Three Molecules Necessary for the Formation of 2SO3?

[muhsentdrawji]

For the reaction, 2SO2(g) +O2 (g) ->2SO3. Why is it wrong to say that the reaction must involve a collision between one O2 and two SO2 molecules? Don't they form S2O6, which is equivalent to the product, 2SO3? What should I say then, about the reactants in forming 2SO3? Thank you so much!

 

[Borek]

It is quite unlikely for three molecules to bump at each other with correct energies at the same time. It is much more likely that the reaction occurs in steps, and the total reaction equation doesn't reflect the mechanism.