Question

Как классифицируют химические реакции по использованию катализатора? Приведите примеры уравнений таких реакций​

Answer 1

Химические реакции по использованию катализатора делят на каталитические и некаталитические.

Каталитические:
2H2O2 MnO₂ ⟶ 2H2O + O2
2KClO3 t,MnO₂ ⟶ 2KCl + 3O2↑

Некаталитические:
4P + 5O2 ⟶ 2P2O5
2Fe + 3Cl2 ⟶ 2FeCl3

Answer 2

Classification of Chemical Reactions Based on Catalyst Usage

Chemical reactions can be classified based on the presence or absence of a catalyst. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It achieves this by providing an alternative reaction pathway with lower activation energy. Here are the main types of chemical reactions based on catalyst usage:

1. Uncatalyzed Reactions: These reactions occur without the presence of a catalyst. The reactants undergo a chemical transformation to form products, but the reaction rate is relatively slow. Examples of uncatalyzed reactions include the combustion of hydrocarbons, such as the reaction between methane (CH4) and oxygen (O2) to form carbon dioxide (CO2) and water (H2O):

   CH4 + 2O2 -> CO2 + 2H2O
   

2. Homogeneous Catalysis: In homogeneous catalysis, the catalyst and the reactants are present in the same phase (usually liquid or gas). The catalyst interacts with the reactants to form an intermediate complex, which then undergoes further reactions to yield the products. An example of a homogeneous catalyzed reaction is the oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3) using vanadium pentoxide (V2O5) as the catalyst:

   2SO2 + O2 + 2V2O5 -> 2SO3 + 4VO2
   

3. Heterogeneous Catalysis: Heterogeneous catalysis involves a catalyst that is in a different phase from the reactants. The reactants adsorb onto the surface of the catalyst, where the reaction takes place. The products then desorb from the catalyst surface. A common example of a heterogeneous catalyzed reaction is the hydrogenation of unsaturated fats using a metal catalyst, such as palladium (Pd):

   C=C + H2 -> C-C
   

4. Enzymatic Catalysis: Enzymes are biological catalysts that facilitate chemical reactions in living organisms. Enzymatic catalysis is highly specific and efficient. Enzymes bind to the reactants (substrates) and facilitate the conversion to products. An example of an enzymatic reaction is the breakdown of hydrogen peroxide (H2O2) by the enzyme catalase:

   2H2O2 -> 2H2O + O2
   

These are just a few examples of the different types of chemical reactions classified based on catalyst usage. The presence of a catalyst can significantly affect the reaction rate and efficiency.