The reaction rate is the rate at which a reactant is consumed or a product is produced. We can determine it by measuring changes in colour, conductivity, pressure, volume, pH, mass, density, or concentration of a reactant or product over a series of time intervals. We usually use concentration:
`r = (Delta c)/(Delta t)`.
Given the rate for one reactant or product in an equation, we can use stoichiometry to determine the rates for the other reactants and products.
There are five main factors that affect the rate of a reaction:
A catalyst is a substance that increases the reaction rate by providing an alternative reaction pathway requiring a lower activation energy, without being consumed itself. If it is in the same phase as all reactants, it is called a homogeneous catalyst; otherwise, it is heterogeneous.