The key difference between chemical kinetics and chemical equilibrium is that chemical kinetics deals with reaction rates, whereas chemical equilibrium deals with the unchanging nature of the concentrations of reactants and products over time.
Chemical kinetics is the branch of physical chemistry concerned with the understanding of the rates of chemical reactions. Chemical equilibrium is the phase where both reactants and products occur in concentrations that have no further intention of changing with time.
CONTENTS
1. Overview and Key Difference
2. What is Chemical Kinetics
3. What is Chemical Equilibrium
4. Chemical Kinetics vs Chemical Equilibrium in Tabular Form
5. Summary – Chemical Kinetics vs Chemical Equilibrium
What is Chemical Kinetics?
Chemical kinetics can be described as the branch of physical chemistry concerned with understanding the rates of chemical reactions. This term is discussed in contrast to thermodynamics. The term chemical kinetics includes the investigation of experimental conditions that can influence the speed of a particular chemical reaction and information regarding the mechanism of the reaction as well as its possible transition states. Moreover, this phenomenon deals with mathematical models describing the characteristics of a reaction.
The major factors that affect chemical kinetics are the nature of the reactants, physical state, surface area of the solid state, concentration, temperature, catalysis, pressure, absorption of light, etc.
There are different methods to determine the reaction rate of a particular chemical reaction. Here, we need to measure the concentration of reactants or products changing over time. E.g. we can measure the concentration of a reactant by spectrophotometry when relating to a wavelength in which no other reactant or product of that system can absorb light.
What is Chemical Equilibrium?
Chemical equilibrium is the phase where both reactants and products occur in concentrations that have no further intention of changing with time. There are reversible chemical reactions as well as irreversible reactions. A chemical reaction involves reactants converting into products. Sometimes, reactants are generated back from the products. These are reversible reactions. But sometimes, the reactants are completely consumed throughout the reaction and are not made again. These are irreversible reactions. In a reversible reaction, when reactants are converting to products, we call it a forward reaction, and when products are converting to reactants, it is a backward reaction.
If the forward and backward reaction rates are equal, then the reaction is at equilibrium. Therefore, over some time, the amount of reactants and products does not change. Reversible reactions always tend to come to equilibrium and maintain that equilibrium. When the system is at equilibrium, the amount of products and the reactants are not necessarily equal. There can be a higher amount of reactants than products or vice versa. The only requirement in an equilibrium equation is the maintenance of a constant amount from both over time. For a reaction in equilibrium, we can define an equilibrium constant as: it is equal to the ratio between the concentration of products and the concentration of reactions.
What is the Difference Between Chemical Kinetics and Chemical Equilibrium?
The terms chemical kinetics and chemical equilibrium are very important in chemistry. These are applied on almost every occasion in nature. The key difference between chemical kinetics and chemical equilibrium is that chemical kinetics deals with the reaction rates, whereas chemical equilibrium deals with the unchanging nature of the concentrations of reactants and products over time.
The below infographic presents the differences between chemical kinetics and chemical equilibrium in tabular form for side-by-side comparison.
Summary – Chemical Kinetics vs Chemical Equilibrium
Chemical kinetics is the branch of physical chemistry concerned with the understanding of the rates of chemical reactions. Chemical equilibrium is the phase where both reactants and products occur in concentrations that have no further intention of changing with time. The key difference between chemical kinetics and chemical equilibrium is that chemical kinetics deals with the reaction rates, whereas chemical equilibrium deals with the unchanging nature of the concentrations of reactants and products over time.
Reference:
1. “Chemical Equilibrium.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.
Image Courtesy:
1. “Activation energy” (Copyrighted free use) via Commons Wikimedia
2. “Chemical Equilibrium” By Fintelia – Own work (CC BY-SA 3.0) via Commons Wikimedia