Question

Define pseudio first order reaction. Show that half life of zero order reaction is directly proportional to concentration of reactant.

Answer 1

If the rate is independent of the concentrations of reactants, the order of reaction is zero. A reaction which is not the first-order reaction naturally but made first order by increasing or decreasing the concentration of one or the other reactant is known as Pseudo first order reaction.

We know, for a Zero order Reaction

$k=\frac{1}{t}\left[A_0\right]-\left[A\right]$

At half life, Conc becomes $\frac{\left[A_0\right]}{2}$.

Substituting, we get

$t_{1/2}=\frac{\left[A_0\right]}{2k}$

$t_{1/2}\propto \left[A_0\right]$.

So, the half-life of zero-order reaction is directly proportional to the concentration of reactant