[DMOC]

Hey guys, I have this reaction:

S₂O₃^2- + 2H⁺   S_(s) + SO_2(g) + H₂O _(l)

Rate law is k[S₂O₃^2-]²[H⁺]⁰

How do I tell what the reaction mechanism could be? And is there more than 1 possibility?

[OrganicSynthesis]

Well by looking at the rate law, you can see that hydrogen ion concentrations do not have an effect on the rate meaning that there is no hydrogen ions in the rate determining step. However, you do see S2O3 ions having a factor. In fact, the rate law is second order with respect to S2O3 ions so you know that the rate determining step has two S2O3 ions reacting.

Otherwise, you have to try and take a logical approach as to what the rest of the reaction mechanism is. If you persevere, I think you will find that it is not that difficult.