Chapter 15, Problem 1DQ

Interpretation Introduction

Interpretation:

The term stability in terms of kinetic and thermodynamic perspective should be explained with the example that shows the differences between them.

Concept Introduction:

Rate of reaction represents the change of concentration of a reactant or a product with respect to time. It can be expressed either by the reduce amount of reactant in per unit time or increase the amount of product in per unit time.

Answer to Problem 1DQ

Kinetically stability depends upon the rate of the reaction whereas thermodynamically stability depends on whether the reaction is favorable or not. The conversion of diamond into graphite is a kinetically stable and thermodynamic unstable.

Explanation of Solution

Kinetic stability of the reaction basically deals with the rate of the reaction. It occurs when reactant reacts very slowly. There is an inverse relationship between rate of reaction and kinetic stability. In other words, when the reaction is slow then it has greater kinetic stability.

Thermodynamic stability of the reaction deals on the spontaneity of the reaction. In other words, it depends on whether the reaction is spontaneous or not and also the change in free energy. It is independent from the pathway followed by the reactants and the products.

Consider an example of conversion of diamond into graphite. It has negative value of $\Delta G$ that means it is a thermodynamically unstable and will occur spontaneously. However, the reaction will take very long time that means it is kinetically stable. Therefore, it is kinetically stable not thermodynamic.

Conclusion

Kinetically stability depends upon the rate of the reaction whereas thermodynamically stability depends on whether the reaction is favorable or not. The conversion of diamond into graphite is a kinetically stable and thermodynamic unstable.