My Dean facepalming icon comes into perfectly appropriate use FAR too often for comfort. If all my other icons go the way of the dinosaur, i feel that one will still be going strong. This one comes a close second.

Um. It's not about the actual ions involved in the redox reaction but rather the strength of the environment the reaction is occuring in, in this case a solution of sodium nitrate whose concentration we have varied. The rate constant was supposed to go up with increasing ionic strenght, in a linear fashion, but of course that's the data I got a U shape for. Wooonderful.