The time for half life period of a certain reaction $A \rightarrow$ products is 1 hour. When the initial…
The time for half life period of a certain reaction $A \rightarrow$ products is 1 hour. When the initial concentration of the reactant ' $A$ ', is $2.0 \mathrm{~mol} \mathrm{~L}^{-1}$, how much time does it take for its concentration to come from $0.50$ to $0.25 \mathrm{~mol} \mathrm{~L}^{-1}$ if it is a zero order reaction?
$4 \mathrm{~h}$
$0.5 \mathrm{~h}$
$0.25 \mathrm{~h}$
$1 \mathrm{~h}$
Solution
For a zero order reaction $k=\frac{x}{t}$
Where $x=$ amount decomposed
$\mathrm{k}=$ zero order rate constant
for a zero order reaction
$
k=\frac{[\mathrm{A}]_0}{2 \mathrm{t}_{\frac{1}{2}}}
$
Since $\left[A_0\right]=2 M, t_{1 / 2}=1 \mathrm{hr} ; \mathrm{k}=1$
$\therefore$ from equation (1)
$\mathrm{t}=\frac{0.25}{1}=0.25 \mathrm{hr}$