Reaction Conditions and rate
Several factors-reactant concentrations, temperature, and presence of catalysts-affect the rate of a reaction. If the reactant is a solid, the surface area available for reaction is also a factor.
The “iodine clock reaction” illustrates the effect of concentration and temperature. The reaction mixture contains hydrogen peroxide (H2O2), iodide ion (I-), vitamin C (ascorbic acid), and starch (which is an indicator of the presence of iodine, I2). A sequence of reaction begins with the slow oxidation of iodide ion to I2 by H2O2