Chapter 9.4, Problem 3QQ

Interpretation Introduction

Interpretation:

The correct option for the given statement has to chosen.

Concept Introduction:

Collision theory:

Collision theory explains why different reactions occurs at different rates.  It is used to explain or predict the rate of a reaction.  For a chemical reaction to occur the molecules or the reacting species must collide with each other.  Chemical reaction is dependent on the number of collisions between the reactants.  The three important parts of collision theory are, the reactant must collide, the reactant must collide with sufficient energy and the collision must be of proper orientation.

Activation Energy:

For a reaction to occur, the reactant molecules must collide with some minimum amount of energy.  This minimum amount of energy for a reaction to occur is known as activation energy.  Every reaction will have different activation energy.  Activation energy is dependent on temperature.  As the temperature increases, molecules will move faster and the activation energy decreases.

Temperature dependence on activation energy:

As the temperature increases, molecules will move faster therefore the molecules will collide easily.  Activation energy will decrease as the temperature increases.  Collisions become easier as the temperature increases.

Rate of a reaction and Activation Energy:

The equation which relates activation energy and rate constant is “Arrhenius Equation”

    ${\text{k=Ae}}^{\frac{{\text{-E}}_{\text{a}}}{\text{RT}}}$

    $\text{k}$ is the rate constant

    ${\text{E}}_{\text{a}}$ is the activation energy

    R is the gas constant

    T is the temperature

    A is the frequency factor

Taking the natural log of both sides, the equation will be like;

    $\text{lnk=lnA-}\frac{{\text{E}}_{\text{a}}}{\text{RT}}$