Question

What is zero order reaction? Explain with suitable examples.

Answer 1

Hint: The rate of progress of the reaction is expressed by its rate law and the order of the reaction can be defined as the sum of the exponents of the concentrations of the reactants.

Complete step by step answer:
The order of the reaction defines the dependence of the rate of progress of the reaction on the concentration of the reactants. In the rate law of an equation, the concentration of the reactants are raised to their stoichiometric coefficient in the balanced chemical equation. These powers are added up to give the order of the reaction. If the order is equal to one then it is known as “first order reaction”, if the order is equal to two, then it is called “second order reaction” and similarly, when the order of the reaction is zero, then it is called “zero-order reaction”.

In the zero-order reactions, the rate of the reaction is independent of the concentration of the reactants. A common example of this type of reaction is reverse of the Haber-Bosch’s process for the synthesis of ammonia. In the Haber-Bosch process, nitrogen and hydrogen combine together to form ammonia. While the reverse of the reaction is not dependent on the concentration of the ammonia formed.

Note:
The time required for the decay of half of the reactant is known as the “half-life” of the reaction and for the “zero-order reactions”, the half-life is equal to $\dfrac{{{\left[ \text{A} \right]}_{\text{0}}}}{\text{2k}}$ where ${{\left[ \text{A} \right]}_{\text{0}}}$ is the concentration of the reactant and k is the rate constant of the reaction.