Question

The half life period of a first order chemical reaction is $6.93$ minutes. The time required for the completion of $99\%$ of the chemical reaction will be ($log2=0.301$) :

• A. $230.3$ minutes
• B. $23.03$ minutes
• C. $46.06$ minutes
• D. $460.6$ minutes

Answer 1

Answer: (C)

$\because \lambda =\frac{0.6932}{t_{1/2}}=\frac{0.6932}{6.93}mi{n}^{-1}$
Also $t=\frac{2.303}{\lambda }log\frac{\left[A_o\right]}{\left[A\right]}$
$\left[A_o\right]=$ initial concentration (amount)
$\left[A\right]=$ final concentration (amount)
$\therefore t=\frac{2.303\times 6.93}{0.6932}log\frac{100}{1}$
$46.06$ minutes