Chemistry - Chemical Kinetics Question with Solution | TestHub

For $1^{\text{st }}$ order reaction

$$\mathrm{A}\to 2\mathrm{B}$$

Initial conc. $0.8-$ After $\mathrm{t}=1\min .0.8-0.8\mathrm{x}1.6\mathrm{x}$ [x dissociation] It is given after 1 min . conc. of $[\mathrm{B}]=1.6\mathrm{x}=0.8$

$$\mathrm{x}=0.5$$

Hence Remaining conc. of $[\mathrm{A}]=0.8-0.8(0.5)=0.4\mathrm{M}$.

For $1^{\text{st }}$ order ${\mathrm{t}}_{{\mathrm{y}}_2}=\frac{0.693}{\mathrm{K}}$

$$\begin{array}{rlr}& \mathrm{K}=\frac{2.303}{\mathrm{t}}{\log }_{10}\left[\frac{{\mathrm{R}}_0}{\mathrm{R}}\right]& \mathrm{K}=\frac{2.303}{60\sec }{\log }_{10}\left[\frac{0.8}{0.4}\right]\end{array}$$

$\mathrm{K}=\frac{0.693}{60}$

$$t_{y_2}=\frac{0.693}{0.693}\times 60$$

$$t_{y_2}=60\sec$$