Chemistry - Chemical Kinetics Question with Solution | TestHub

For a first-order reaction, the rate constant is given by:

$k=\frac{2.303}{t}\log \left(\frac{a}{a-x}\right)$

Substituting the given values ($t=20$ min, $x=15\%$):

$k=\frac{2.303}{20}\log \left(\frac{100}{100-15}\right)$

$k=\frac{2.303}{20}\log \left(\frac{100}{85}\right)$

$k=\frac{2.303}{20}\times 0.0706\approx 0.0081{\text{min}}^{-1}$

Answer: $0.0081{\text{min}}^{-1}$