CBSE Class 12 Chemistry Notes: Chemical Kinetics – Arrhenius Equations

The effect of temperature on rate is given by Arrhenius law
k = A.e^–E/RT            K = rate constant

    E = Activation energy

    R = Gas constant

    T = Absolute Temp.

    A = Frequency factor (Arrhenius Constant)

Taking log an both order
 

On comparing with the equation of line

From the above equation it is clear that when T → ∞ then k becomes A.
i.e. Arrhenius constant is that value of rate constant at infinite temperatures.
Now on comparing Arrhenius equation with equation of straight line we have

Pre exponential factor

The effect of temperature on rate of reaction at two different temperature T₁& T₂ can be calculated by the Arrhenius law.

Surface Area of Reactants:

In Solid reactions, surface area plays an important role. Larger surface area provides more active sites for reaction hence increase the rate of reaction whereas small surface areas decrease the rate of reaction.

Fine particle         – Large surface area
     Big size particle   – Small surface area

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