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Half life period of a reaction is defined as the time taken for the concentration of a reactant to reduce to one half of its initial concentration.

For a zero order reaction, t_{1/2} can be calculated as follows,

A → Products

The integrated equation

[A] = -kt + [A]_{o}

At t =t_{1/2}, [A] = [A]_{0}/2

[A]_{0}/2 = -kt_{1/2} + [A]_{o}

[A]_{0}/2 - [A]_{o} = -kt_{1/2}

-[A]_{0}/2 = -kt_{1/2}

t_{1/2} = [A]_{0}/2

t_{1/2} ∝ [A]_{0}

Half life for a zero order reaction is directly proportional to the initial concentration of the reactants .

For a first order reaction, t1/2 can be calculated as,

A → Products

The integrated equation

k = 2.303/t . log([A_{0}]/[A])

t = t_{½}; [A]:[A_{0}]

k = 2.303/t_{½} . log([A_{0}]/[A_{0}/2])

t_{½ }= (2.303 x log 2)/k

t_{½ }= (2.303 x 0.301)/k

t_{½ }= 0.693/k

Half life period for a first order reaction is independent of the initial concentration of the reactant.

Half life period of a reaction is defined as the time taken for the concentration of a reactant to reduce to one half of its initial concentration.

For a zero order reaction, t_{1/2} can be calculated as follows,

A → Products

The integrated equation

[A] = -kt + [A]_{o}

At t =t_{1/2}, [A] = [A]_{0}/2

[A]_{0}/2 = -kt_{1/2} + [A]_{o}

[A]_{0}/2 - [A]_{o} = -kt_{1/2}

-[A]_{0}/2 = -kt_{1/2}

t_{1/2} = [A]_{0}/2

t_{1/2} ∝ [A]_{0}

Half life for a zero order reaction is directly proportional to the initial concentration of the reactants .

For a first order reaction, t1/2 can be calculated as,

A → Products

The integrated equation

k = 2.303/t . log([A_{0}]/[A])

t = t_{½}; [A]:[A_{0}]

k = 2.303/t_{½} . log([A_{0}]/[A_{0}/2])

t_{½ }= (2.303 x log 2)/k

t_{½ }= (2.303 x 0.301)/k

t_{½ }= 0.693/k

Half life period for a first order reaction is independent of the initial concentration of the reactant.