Question

The label on a bottle of 3% (by volume) hydrogen peroxide, h2o2, purchased at a grocery store, states that the solution should be stored in a cool, dark place. h2o2 decomposes slowly over time, and the rate of decomposition increases with an increase in temperature and in the presence of light. however, the rate of decomposition increases dramatically if a small amount of powdered mno2 is added to the solution. the decomposition products are h2o and o2. mno2 is not consumed in the reaction. what role does mno2 play? how do you know this?

Answer 1

MnO2 acts as a catalyst in the decomposition of H2O2, speeding up the reaction without being consumed, evidenced by the rapid evolution of water and oxygen gas.

Step-by-step explanation:

The role of MnO2 in the decomposition of hydrogen peroxide (H2O2) is that of a catalyst. Since the rate of decomposition of H2O2 increases dramatically when MnO2 is added but MnO2 itself is not consumed in the reaction, we can deduce that it's acting as a catalyst. Catalysts work by providing an alternate reaction pathway with a lower activation energy, which significantly speeds up the reaction rate without being consumed themselves. This is supported by experiments where adding MnO2 to H2O2 leads to the rapid production of water (H2O) and oxygen gas (O2), visible as bubbling in the reaction mixture.

Manganese dioxide (MnO2) plays the role of a catalyst in the decomposition of hydrogen peroxide (H2O2). A catalyst increases the rate of a chemical reaction without being consumed in the reaction. In the presence of MnO2, the decomposition of H2O2 into water (H2O) and oxygen gas (O2) occurs rapidly, unlike the slow decomposition in the absence of a catalyst.