Question

For the zero order reaction, $\text{A} \rightarrow \text{B} + \text{C}$ ; initial concentration of A is 0.1 M. If [A] = 0.08 M after 10 minutes, then it's half life and completion time are respectively

• A. $10 \, \text{min} \text{, } 20 \, \text{min}$
• B. $25 \, \text{min} \text{, } 50 \, \text{min}$
• C. $2 \times 1 0^{- 3} \text{min} \text{, } 4 \times 1 0^{- 3} \text{min}$
• D. $250 \, \text{min} \text{, } 500 \, \text{min}$

Answer 1

Answer: (B)

For zero order reaction $\Rightarrow \text{C}_{\text{t}} = \text{C}_{0} - \text{kt}$

So, $\text{k} = \frac{\text{C}_{0} - \text{C}_{\text{t}}}{\text{t}} = \frac{0.1 - 0.08}{10} = 2 \times 10^{- 3}$

$\text{T}_{1 / 2} = \frac{\text{C}_{0}}{2 \text{k}} = \frac{0.1}{2 \times 2 \times 10^{- 3}} = 25 \, \text{min}$

$T _{100 \%}=\frac{ C _{0}}{ k }=\frac{0.1}{2 \times 10^{-3}}=\frac{100}{2}=50 min$