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 (log 2 = 0.301)

• A. 23.03 minutes
• B. 46.06minutes
• C. 460.6 minutes
• D. 230.03 minutes

Answer 1

Answer: (B)

46.06minutes

Answer 2

For first order reaction,
$k=\frac{0.693}{t_{1 /2} }=\frac{0.693}{6.93}$
$k=\frac{2.303}{t} \, log\, \frac{100}{100-99}$
$\frac{0.693}{6.93}=\frac{2.303}{t} log\, \frac{100}{1}$
$\frac{0.693}{6.93}=\frac{2.303\times2}{t}$
t=46.06 min