Do the reaction rate depends on the concentration of catalyst?
I googled this and found that the decomposition of H2O2 stops of we add excess MnO2.
Are there any other examples like this? Or does this happens with every catalyst when they are in excess or they are in very smaller amounts?(But I've learned that a very small amount of the catalyst is usually needed to increase the reaction rate)
I think you misunderstood the site where you obtained that information. A catalyst does speed up the reaction and only minimum amounts are needed. Increasing the catalyst increases the rate UP TO A POINT. When you say increasing the amount of catalyst STOPS if we add excess MnO2, this means THE REACTION RATE STOPS INCREASING. It doesn't mean that it shuts down the decomposition of H2O2. The decomposition still takes place, you've simply reached the point at which more and more MnO2 has no effect on the rate; i.e., you have reached the maximum rate of decomposition. I hope that is clear enough to you although the wording sounds a little awkward to me. But I didn't want to rewrite it.
I understand and thank you very much!
The reaction rate of a reaction typically depends on several factors, including the concentration of the reactants, temperature, pressure, and the presence of any catalysts.
Catalysts are substances that can speed up the rate of a chemical reaction without being consumed in the process. In the case of the decomposition of H2O2 (hydrogen peroxide), MnO2 (manganese dioxide) acts as a catalyst. When MnO2 is added in excess, it can absorb all the available hydrogen peroxide, thus stopping the reaction.
While this is an example of the reaction rate depending on the concentration of a catalyst, it does not hold true for every catalyst. Some catalysts work by providing a surface for the reactant molecules to react on, creating an environment that facilitates the reaction. In these cases, a small amount of catalyst is generally needed to increase the reaction rate. The reaction rate may plateau or be relatively unaffected if the catalyst is present in excess.
However, it is important to note that the effect of a catalyst on the reaction rate can vary greatly depending on the specific reaction and the properties of the catalyst. Some catalysts may be more efficient at lower concentrations, while others may require higher concentrations to have a significant effect. It is always advisable to consult specific references or conduct experiments to determine the optimal conditions for a particular catalyst and reaction.