zero order reaction

A chemical reaction is a process that results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants. Chemical reactions are usually characterized by a chemical change, and they yield one or more products which are, in general, different from the reactants. Classically, chemical reactions encompass changes that strictly involve the motion of electrons in the forming and breaking of chemical bonds, although the general concept of a chemical reaction, in particular the notion of a chemical equation, is applicable to transformations of elementary particles, as well as nuclear reactions.
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According to IUPAC Compendium of Chemical Terminology the rate law or rate equation for a chemical reaction is an equation which links the reaction rate with concentrations or pressures of reactants and constant parameters (normally rate coefficients and partial reaction orders). To determine the rate equation for a particular system one combines the reaction rate with a mass balance for the system . For a generic reaction A + B → C the simple rate equation (as opposed to the much more common complicated rate equations) is of the form:
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Compare with first order reaction and second order reaction .A reaction with a reaction rate that does not change when reactant concentrations change.