A catalyst increases the rate of a chemical reaction without taking part in the chemical reaction. And can be recovered end of the reaction. The phenomenon of increasing the reaction rate with the help of a catalyst is known as catalysis.
The following characteristic is most common in catalytic reactions.
- At the end of the reaction, a catalyst’s amount and chemical composition remain unchanged.
- Catalysts are needed in only a small quantity.
- In a reversible reaction, the catalyst does not change the equilibrium position. Bodenstein was able to show that the use of a catalyst hastened the approach of equilibrium in the decomposition of hydrogen iodide. It did not alter the concentration of the reactants or the products. It is found to be true in many other reversible reactions as well.
- Those reactions are extremely slow in the absence of a catalyst. The function of the catalyst is only to speed up the reaction rate. The catalyst does not initiate the reaction. The reaction in the presence of a catalyst takes place through some alternative path that requires much lower activation energy. So, it is speeded up.
- The catalyst is specific in its reaction. For example, manganese dioxide can catalyze the decomposition of potassium chlorate but not that of potassium perchlorate or potassium nitrate. Thus, manganese dioxide is specific in its action.
- Catalysts cannot change the nature of the product of the reaction. For example, on decomposition, potassium chlorate gives potassium chloride and oxygen if catalyst manganese dioxide is added or not.
- A particular substance poisons a catalyst. It was found that impurities of any type, even if present in small amounts, inhibit the rate of catalyzed reactions to a large extent. These impurities are called catalytic poisons.
There are two types of catalysis
What is Homogenous catalysis?
When the reactant and the catalyst both are in a single phase called homogenous catalysis. (i.e. solid, liquid, gas)
\[\displaystyle 2SO{}_{{2(g)}}+{{O}_{{2(g)}}}\underset{{}}{\overset{{N{{O}_{{(g)}}}}}{\longrightarrow}}2S{{O}_{{3(g)}}}\]
What is Heterogeneous catalysis?
When the catalyst and reactant both are in different phases called heterogeneous catalysis. (i.e. solid (reactant) liquid (gas)
\[\displaystyle C{{O}_{{(g)}}}+3{{H}_{2}}_{{(g)}}\underset{{}}{\overset{{C{{o}_{{(s)}}}}}{\longrightarrow}}C{{H}_{{4(g)}}}+{{H}_{2}}{{O}_{{(g)}}}\]
