In collision theory of chemical reaction, `Z_(AB)` represents

Options

A. the fraction of molecules with energies greater than `E_a`
B. the collision frequency of reactants, A and B
C. steric factor
D. the fraction of molecules with energies equal to `E_a`

Answer

To solve the question regarding what \( Z_{AB} \) represents in the collision theory of chemical reactions, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Collision Theory**:
Collision theory states that for a reaction to occur, reactant molecules must collide with sufficient energy and proper orientation.

2. **Define Collision Frequency**:
The symbol \( Z \) in the context of collision theory represents the collision frequency, which is the number of collisions per second per unit volume of the reaction mixture.

3. **Identify the Reaction Type**:
In this case, we are considering a bimolecular reaction, which involves two reactants, A and B.

4. **Write the Reaction**:
The bimolecular reaction can be represented as:
\[ A + B \rightarrow \text{Products} \]

5. **Express the Rate of Reaction**:
The rate of reaction for this bimolecular reaction can be expressed mathematically as:
\[ \text{Rate} = Z_{AB} e^{-\frac{E_a}{RT}} \]
where:
- \( Z_{AB} \) is the collision frequency of the reactants A and B.
- \( E_a \) is the activation energy.
- \( R \) is the universal gas constant.
- \( T \) is the temperature in Kelvin.

6. **Conclude the Meaning of \( Z_{AB} \)**:
From the above expression, it is clear that \( Z_{AB} \) specifically represents the collision frequency of the reactants A and B in the reaction.

### Final Answer:
Thus, in the collision theory of chemical reactions, \( Z_{AB} \) represents the collision frequency of the reactants A and B.

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