The rate of reaction increases by the increase of temperature because

Options

A. colliison frequency is increased.
B. Energy Products decreases.
C. Fraction of molecules possesisng energy `ge E_(T)` (threshold energy) increases.
D. Meachanism of a reaction is changed.

Answer

To understand why the rate of reaction increases with temperature, we can break down the explanation into several steps:

### Step 1: Understand the Arrhenius Equation
The Arrhenius equation is given by:
\[ k = A e^{-\frac{E_a}{RT}} \]
Where:
- \( k \) is the rate constant,
- \( A \) is the pre-exponential factor (frequency factor),
- \( E_a \) is the activation energy,
- \( R \) is the universal gas constant,
- \( T \) is the temperature in Kelvin.

### Step 2: Analyze the Effect of Temperature on the Rate Constant
From the Arrhenius equation, we can see that as the temperature \( T \) increases, the term \( \frac{E_a}{RT} \) decreases. This results in an increase in the exponential term \( e^{-\frac{E_a}{RT}} \), which means that the rate constant \( k \) increases.

### Step 3: Fraction of Molecules with Sufficient Energy
The fraction of molecules that possess energy greater than the activation energy \( E_a \) can be represented as:
\[ x = e^{-\frac{E_a}{RT}} \]
As temperature increases, \( x \) increases because the exponent becomes less negative, indicating that a larger fraction of molecules have energy greater than \( E_a \).

### Step 4: Effective Collisions
For a reaction to occur, reactant molecules must collide with sufficient energy (greater than \( E_a \)). As the fraction of molecules with energy greater than \( E_a \) increases, the number of effective collisions also increases.

### Step 5: Conclusion
Since the rate of reaction is directly proportional to the number of effective collisions, an increase in temperature leads to an increase in the rate of reaction. Thus, the correct answer to the question is that the fraction of molecules possessing energy greater than the threshold energy increases when we increase the temperature.

### Final Answer
The rate of reaction increases with temperature because the fraction of molecules possessing energy greater than the activation energy increases.

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