Question

What is the half life of a chemical reaction?

Answer 1

For a chemical reaction:

$R\to P$

The half-life is defined as the time in which the concentration of the reactant ($R$) is reduced to half of its initial concentration $\left[R_0\right]$. It is represented as $t_{1/2}$

Time $t=0,\left[R\right]=\left[R_0\right]$

and for, $t=t_{1/2}$

$\left[R\right]=\left[R_{t_{1/2}}\right]$

By definition, $\left[R_{t_{1/2}}\right]=\frac{1}{2}{[R}_0]$

$where{[R}_0]=$ initial reactant concentration i.e. at $t=0$