Effect Of Catalyst In Rate Of Reaction Flashcards
What is a catalyst?
A catalyst is a substance which alters the rate of chemical reaction by lowering the activation energy.
Describe mathematically the relationship between the rate constant and the activation energies of catalysed and non-catalysed reaction.
Log(K2/K1) = (Ea1 - Ea2)/(2.303RT)
Where K2 = rate constant of the catalysed reaction
K1 = rate constant of un-catalysed reaction
Ea1 = activation energy of un-catalysed reaction
Ea2 = activation energy of catalysed reaction
R = 8.314
T = temperature
What are the types of catalysis?
Homogenous and Heterogeneous catalysis
What is homogenous catalysis?
Homogenous catalysis is a type of catalysis where the catalyst is in the same physical state as the reactant and product in the catalysed reaction.
What is heterogeneous catalysis?
This is a type of catalysis where the catalyst is in a different physical state as the reactant or product.
What is the major advantage of homogenous catalysis?
The catalysis occurs throughout the whole mixture.
What is the major disadvantage of homogenous catalysis?
It is almost always impossible to extract the catalyst from the product because the catalyst and the product are in the same phase.
What are the examples of homogenous catalysis?
These include hydrolysis and esterification.
What are the examples of Heterogeneous catalysis?
- Contact process (production of S03 from S02 and ½O2 with veradium (v) oxide as catalyst)
- Haber process (production of ammonia with finely divided iron as catalyst)
What is reaction mechanism?
This is the sequence of elementary steps by which a chemical reaction occurs.
What is the chemical equation for the Contact Process?
S02 + ½O2 ==(V2O2)==> SO3
Where V2O2 is veradium (v) oxide.
What is the chemical equation for the Haber process?
N2 + 3H2 ==Fe==> 2NH3
Where Fe is the finely divided iron that serves as catalyst. All are gases except for the catalyst.
What is an intermediate?
An intermediate is a species that is produced in one step and used up in the next step.
What are the requirements for a chemical mechanism to be acceptable?
- The sum of elementary steps must give the balanced overall equation.
- The mechanism must agree with the experimentally determined rate’s law.
