CBSE · Class 12 · Chemistry · Chemical KineticsExplain the term 'activation energy' and describe how temperature affects the rate of a chemical reaction using the Arrhenius equation.

Activation energy ($E_a$) is defined as the minimum extra amount of energy that reactant molecules must possess in order to undergo a chemical reaction and be converted into products. It represents the energy barrier that must be overcome for reactants to transform into products during a collision. \nAccording to Arrhenius, the rate constant of a reaction is related to temperature by the Arrhenius equation: $$k = A e^{-E_a / RT}$$\nWhere $k$ is the rate constant, $A$ is the Arrhenius factor (frequency factor), $E_a$ is activation energy, $R$ is the gas constant, and $T$ is absolute temperature. \nTaking natural logarithm on both sides: $$\ln k = \ln A - \frac{E_a}{RT}$$\nConverting to base 10: $$\log k = \log A - \frac{E_a}{2.303 RT}$$ \nThis equation shows that as the temperature ($T$) increases, the fraction of molecules having energy greater than or equal to activation energy increases, which exponentially increases the rate constant ($k$), and consequently, the rate of the chemical reaction increases significantly.