See explanation below.
Work Step by Step
The reaction rate (rate of reaction) or speed of reaction for a reactant or product in a particular reaction is intuitively defined as how quickly or slowly a reaction takes place. For example, the oxidative rusting of iron under Earth's atmosphere is a slow reaction that can take many years, but the combustion of cellulose in a fire is a reaction that takes place in fractions of a second. The reaction rate depends on the concentration of reactants involved, which decreases during the course of the reaction. Due to this change in concentration, reaction rate varies with time even when temperature is constant.