Catalyst in Chemistry is defined as a substance that alters the rate of a chemical reaction but remains unchanged at the end of the reaction.
A catalyst is a substance that speeds up the rate of reactions but it does that by affecting the activation energy of the reaction.
Activation energy is the minimum amount of energy that must be attained or surpassed before a chemical reaction will occur.
It is important to note that a catalyst could be positive or negative. A positive catalyst speeds up the rate of reaction by reducing the activation energy while a negative catalyst slows down the rate of a chemical reaction by increasing the activation energy.
Properties of a Catalyst
- A catalyst remains unchanged at the end of a reaction
- A catalyst is specific in function
- A catalyst alters the activation energy
- A catalyst retains its chemical composition after reaction
- A catalyst(positive catalyst) reduces the time taken to achieve equilibrium
- A catalyst does not affect the equilibrium position of a chemical reaction
Examples of Catalysts in Chemical reactions
Some examples of catalysts in chemical reactions for specific purposes are listed below with the specific catalyst.
Please note that some reactions can be catalyzed and occur faster only in the presence of catalyst but some other reactions cannot be catalyzed at all but however can be influenced by other factors affecting rates of reactions.
Catalyst in Chemistry and rate of reaction
The rate of a reaction can be hastened or increased by so many factors including Temperature, Concentration, Pressure, Presence of Light and even Catalyst.
I won’t go into details o how these factors affect the rate of reactions because I have already written a well-researched post on Factors affecting rates of reactions.
However, I will talk a little about the effect of a catalyst on the rate of a reaction.
The rate of a reaction affected by a catalyst is via activation energy. Please recall that there are basic parameters that once affected can alter the rate of a reaction.
The parameters are frequency of collision, the average kinetic energy of the particles and activation energy of the reaction. A catalyst does not affect any other factor except the activation energy of the particles.
What a catalyst does is reduce the activation energy of the reaction thereby making it easier for the reactant particles to collide and garner sufficient energy equal to or more than the activation thus providing an alternative pathway for the reaction to follow.
Recall that activation energy is the minimum amount of energy required for the reactant particles to attain or surpass before the reaction will occur if the activation energy is high particles will struggle to attain or overcome it but if it is low it will be easy to attain or surpassed.
A catalyst in Chemistry helps the reactant particles by reducing that stress for them as it lowers that minimum amount of energy.
Importance of a catalyst in Chemistry and industry
Catalyst Chemistry Concept is a very vital important concept in Chemistry because a catalyst saves up time for us. Some reactions would have taken so many hours without the effect of a catalyst.
A catalyst is quite beneficial because it increases productivity in Industries by speeding up the rate of the reaction.
Energy and Resources is also economized with the effect of a catalyst since it reduced the excessive collisions making production cheaper and more effective.
Two Types of Catalysts used in Chemistry
There are two basic types of catalysts used in Chemistry; have homogeneous catalysts and heterogeneous catalysts.
Homogeneous catalysts have a uniform composition with the reactants or reactant mixture while heterogeneous catalysts do not necessarily need to be in the same composition with the reactants.
Few Examples of Catalyzed reactions
- Haber Process for Ammonia
N2 + 3H2 –> 2NH3
Haber process is a process for the manufacture of ammonia. This reaction is catalysed by the presence of iron filings.
2. Contact process for the production of sulphuric acid
The first stage is the formation of sulphur VI oxide
2SO2 + O2 –> 2SO3
The catalyst used is vanadium V oxide
3. Hydrogenation of oil to form margarine or butter
The hydrogenation of oil or hardening of oil is used to convert oil to solid fats (margarine or butter)
The catalyst used is Nickel.
4. Decomposition of Hydrogen Peroxide
The decomposition of Hydrogen Peroxide to form water and oxygen is catalyzed by manganese iv oxide.
2H2O2 –> 2H2O + O2
5. Cracking of Hydrocarbons
Hydrocarbons are cracked into more useful but lighter hydrocarbons. though we have thermal cracking, steam cracking and catalytic cracking.
Catalytic cracking is hastened by zeolites or aluminium oxide.
6. Conversion of poisonous carbon monoxide into carbon iv oxide in the exhaust pipe
There is a need to monitor the level of pollution in our environment and one of the ways poisonous gases get into our environment is via exhaust pipes from cars.
With the introduction of catalytic converters fixed at exhaust pipes of cars poisonous gases like nitrogen II oxide (NO), nitrogen IV oxide (NO2)and CO can be converted into nonpoisonous gases like Nitrogen and carbon IV oxide with the help of catalysts like Platinum and Rhodium.
7. Isomerization reactions
Isomerism in Chemistry is a phenomenon whereby an organic compound will have the same molecular formula but different structural formula.
For example conversion of normal butane to 2 methyl propane (isobutane) is aided by the presence of Aluminium chloride.
8. Esterification reaction
An esterification reaction is a reaction in which carboxylic acid reacts with alcohol to form ester and water.
This reaction is catalysed by the presence of sulphuric acid
CH3COOH + CH3OH –> CH3COOCH3 + H2O
9. Substitution reaction of Alkanes
Alkanes can undergo substitution reactions only in the presence of ultraviolet light. The light acts as a catalyst and such reactions are said to be photochemical reactions.
In this case, light is the catalyst.
This is another example of Catalyst Chemistry but equally a photochemical reaction. In this reaction, carbon iv oxide and water combine to form glucose and oxygen.
The chlorophyll and light can be likened to the catalyst.
6CO2 + 6H2O –> C6H12O6 + 6O2
In conclusion, it is important to mention that transition elements and compounds are commonly used as catalysts in Chemistry.
Catalyst Chemistry is a very important aspect of chemistry that cuts across several reactions and processes.