The rate of a chemical reaction generally increases rapidly even for small temperature rise because of rapid increases in the

Options

A. Colliison frequency
B. Activation energy
C. Fraction of molecules with energies in exess of the activation energy
D. Avergae kinetic energy of the molecules

Answer

To solve the question regarding why the rate of a chemical reaction increases rapidly even for a small rise in temperature, we can follow these steps:

### Step 1: Understand the Relationship Between Temperature and Reaction Rate
The rate of a chemical reaction is influenced by temperature. As the temperature increases, the kinetic energy of the molecules also increases, which leads to more frequent and energetic collisions between reactant molecules.

**Hint:** Consider how temperature affects the motion of molecules.

### Step 2: Define Activation Energy
Activation energy (Ea) is the minimum energy required for a reaction to occur. It is the energy barrier that must be overcome for reactants to be transformed into products.

**Hint:** Think about what energy is needed for a reaction to proceed.

### Step 3: Analyze the Effect of Temperature on Activation Energy
When the temperature rises, a greater fraction of molecules have energy equal to or greater than the activation energy. This is described by the Arrhenius equation, which shows that the rate constant (k) increases exponentially with an increase in temperature.

**Hint:** Recall the Arrhenius equation and how it relates temperature to reaction rates.

### Step 4: Fraction of Molecules with Energy Greater than Activation Energy
The fraction of molecules that possess energy greater than the activation energy increases with temperature. This means that more molecules can successfully collide and react, leading to an increase in the reaction rate.

**Hint:** Consider how the distribution of molecular energies changes with temperature.

### Step 5: Conclusion
Thus, the correct answer to the question is that the rate of a chemical reaction increases rapidly even for small temperature rises because of the rapid increase in the **fraction of molecules with energy in excess of activation energy**. This allows for more effective collisions, resulting in a higher reaction rate.

**Final Answer:** The correct option is **C: Fraction of molecules with energy in excess of activation energy**.

---