I^-: I^-, or iodide ion, is a negatively charged atom of iodine. It plays a role in the reaction by reacting with H2O2 in Step 1.
IO^-: IO^-, or hypoiodite ion, is a negatively charged molecule containing one iodine atom and one oxygen atom. It forms in Step 1 and reacts further in Step 2.
Rate Law: The rate law describes the relationship between the concentrations of reactants and the rate of a chemical reaction. In this context, it would describe how the concentration of H2O2 affects the overall reaction rate.