Question

99% of a first order reaction was completed in 32min. When will 99.9% of the reaction complete ?

• A. 50 min
• B. 46 min
• C. 49 min
• D. 48 min

Answer 1

Answer: (D)

$k=\frac{2.303}{t}\log \frac{100}{100-x}$
Substituting the values,
$k=\frac{2.303}{32}\log \frac{100}{1}$
$k=0.144{\min }^{-1}$
$t=\frac{2.303}{0.144}\log \frac{100}{0.1}$
$t=48min$