A zero-order reaction is a type of chemical reaction in which the rate of reaction is independent of the concentration of one or more of the reactants. In a zero-order reaction, the rate of reaction remains constant over time, and it is not influenced by changes in the concentration of the reactants.
The general form of a zero-order reaction can be expressed as follows:
Rate = k
Where:
“Rate” is the rate of the reaction (the change in concentration of a reactant or product per unit of time).
“k” is the rate constant, which is a constant value specific to the reaction at a given temperature.
Key characteristics of zero-order reactions:
Constant Rate: The rate of the reaction remains constant throughout the reaction, regardless of changes in the concentration of reactants.
Graphical Representation: On a concentration-versus-time graph, a zero-order reaction appears as a straight horizontal line with a constant slope, indicating that the rate of change is uniform.
Half-Life: In zero-order reactions, the half-life of the reaction (the time it takes for the concentration of a reactant to decrease by half) is directly proportional to the initial concentration of the reactant. The higher the initial concentration, the longer the half-life.
Zero-order reactions are relatively rare and are usually observed when the reaction rate is limited by factors other than reactant concentrations, such as a catalyst or a surface reaction with a solid catalyst. Examples of zero-order reactions include certain enzyme-catalyzed reactions and reactions on solid surfaces.
It’s important to note that zero-order reactions are the exception rather than the rule, as most chemical reactions are influenced by the concentrations of reactants and follow first-order or higher-order kinetics.