Limitation of chemical reaction:\tIt does not mention the state of the substances. So (s) for solid, (l) for liquid, (g) for gas and (vap) for vapor may be added.\tThe reaction may or may not be complete. Equation does not reveal it.\tIt does not give any information regarding the speed of the reaction.\tIt does not give the concentration of the substances. In some cases, terms like diluted and concentrated may be added.\tIt does not give the conditions of temperature, pressure, catalyst, etc. This is overcome by mentioning these above or below the arrow .\tIt does not give any idea about color changes, which has to be mentioned separately.