Chemistry class 12th Frequency factor explanation

Frequency Factor in Chemical Kinetics




Introduction
The frequency factor (A) is an important term in the Arrhenius
equation, which describes
how the rate constant (k) of a chemical reaction depends on
temperature and activation energy.

Arrhenius Equation
The Arrhenius equation is given by:

k = A * e^(-Ea / (RT))

Where:
- k = rate constant
- A = frequency factor (pre-exponential factor)
- Ea = activation energy (J/mol)
- R = universal gas constant (8.314 J/mol*K)
- T = absolute temperature (K)
- e = mathematical constant (approximately 2.718)

Significance of Frequency Factor
The frequency factor (A) represents the number of times reactant
molecules collide with
the correct orientation per unit time. It is directly related to the
likelihood of a successful
reaction occurring.

Factors Affecting Frequency Factor
1. Molecular Orientation - Proper alignment of molecules increases A.
2. Nature of Reactants - More complex molecules tend to have lower
A values.
3. Reaction Medium - Solvents and phase of reactants affect A.
4. Catalysts - Catalysts can alter A by providing alternative reaction
pathways.