Question

Explain zero order reaction with example.

Answer 1

Hint: Chemical kinetics describes the rate of the reaction taking place in nature at some conditions suitable for the same. Rate of reaction is decided by the order of the reaction taking place as first order, second order, zero order, pseudo first order, etc.
One of them is zero order reaction in which the reaction taking place does not depend upon the concentrations of the reactants reacting.

Complete answer:
Let us study what we actually mean by zero order reactions;
The reactions in which the concentration of the reactants does not change with time and thus the rate remains constant is known as zero order reactions. In short, if we increase or decrease the concentration of the reactants, the rate of reaction cannot be affected.
This can be represented as,
For the reaction- $A+B\to Products$ , the rate is given as;
$Rate=k{{\left[ A \right]}^{0}}{{\left[ B \right]}^{0}}=k$ where, k is the rate constant.
Facts-
-In zero order reactions, increasing the concentration of reactant species will not speed up the rate of the reaction.
-They are typically found in the material (catalyst surface) required for the reaction and are surrounded by the reactants.
-If the data of concentration is plotted against the time curve, then the resulting curve will be a straight line.
Examples-
1. Photochemical reaction-
The reaction of hydrogen with chlorine is known as a photochemical reaction which is a zero-order reaction.
     \[{{H}_{2}}_{\left( g \right)}+C{{l}_{2}}_{\left( g \right)}\xrightarrow{h\nu }2HC{{l}_{\left( g \right)}}\]
2. Decomposition of nitrous oxide over a hot plate of platinum acting as a catalyst surface.
     \[2{{N}_{2}}O\xrightarrow{Pt\left( hot \right)}2{{N}_{2}}+{{O}_{2}}\]

Note:
Do note the reaction will stop in the case of zero order reaction when the reactants are completely exhausted.
Zero order reactions are different from first order and second order reactions as the rate will be always constant here irrespective of the concentration of reacting species.