Threshold energy( ET) The minimum amount of energy which the reactant must possess in order to convert into products is known as threshold energy.
Activation energy( Ea) The additional amount of energy, required by the reactant so that their energy becomes equal to the threshold value is known as activation energy.
⇒ Ea = ET – ER
Lower the activation energy, faster is the reaction.
Different reactions have different rates because their activation energies are different.
Larger the value of Eo, smaller the value of rate constant and greater is the effect of a given temperature rise on K
Important points about Arrhenius equation( i) If R2 and R1 are rate constant at temperature T2 and T1; then
ii) Fraction of molecules with energy equal to or greater than the activation energy is called Boltzmann factor and is given by
( ii) Ea is constant for a particular reaction.
( iii) Ea does’ t depend on temperature, volume, pressure, etc., but gets affected by catalyst.