The addition of a specific catalyst to the decomposition of hydrogen peroxide can significantly increase the reaction rate. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It does this by lowering the activation energy required for the reaction to occur, which allows more reactant molecules to have sufficient energy to react.In the case of hydrogen peroxide H2O2 decomposition, the reaction can be slow at room temperature without a catalyst. The reaction is as follows:2 H2O2 aq 2 H2O l + O2 g When a catalyst, such as manganese dioxide MnO2 , potassium iodide KI , or catalase an enzyme found in living organisms , is added to the hydrogen peroxide solution, the reaction rate increases dramatically. These catalysts provide an alternative reaction pathway with a lower activation energy.For example, when using manganese dioxide as a catalyst, the reaction proceeds as follows:1. MnO2 s + H2O2 aq MnO OH s + H2O l + O2 g 2. MnO OH s + H2O2 aq MnO2 s + 2 H2O l In this case, the manganese dioxide is not consumed in the overall reaction, as it is regenerated at the end of the second step. The net reaction remains the same as the uncatalyzed decomposition:2 H2O2 aq 2 H2O l + O2 g The increased reaction rate can be observed by the rapid evolution of oxygen gas bubbles and the faster formation of water. The use of catalysts in the decomposition of hydrogen peroxide is important in various applications, such as the breakdown of hydrogen peroxide in living cells by catalase to prevent cellular damage or the use of hydrogen peroxide as a propellant in rocket engines.