Determination of Reaction Rate for the Iodination of Acetone

Question

If NaI is added to the reaction, what effect will this have on the reaction?

Answer 1

The equation for this reaction (all species being aqueous) would look something like this:

acetone + iodine + acid ==> iodoacetone + iodide ion + hydronium ion

CH₃(C=O)CH₃ + I₂ + H⁺ ==> CH₃(C=O)CH₂I + I^- + H⁺

The initial reaction rate would likely not be affected by addition of NaI because neither Na⁺ nor I^- are reactants, but at equilibrium the reaction will be shifted to the reactant side. This is based on Le Chatelier's Principle because addition of NaI increases the concentration of I- (a product). However, note that this is relevant for systems at equilibrium. Since reaction rates are generally determined during initial rates, this would not be a determining factor.