1. Tardigrade
  2. Question
  3. Chemistry
  4. t1/2 for a first order reaction is 14.26 min. Calculate the time when 5 % of the reactant is left.

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. $t_{1/2}$ for a first order reaction is $14.26\, min$. Calculate the time when $5\%$ of the reactant is left.

UP CPMTUP CPMT 2015Chemical Kinetics

Solution:

$x=100\%-5\%=95\%$
$k=\frac{0.693}{t_{1 /2}}=\frac{0.693}{14.26}=0.0486$
$k=\frac{2.303}{t}log \frac{a}{a-x}$
$t=\frac{2.303}{0.0486}log \frac{100}{100-95}$
$t=61.65\,min\, \approx 62\,min$