Question

A first-order reaction was 70 percent complete in 20 minutes. What is the rate constant of the reaction?

(a) 0.07 min^-1

(b) 0.06 min^-1

(c) 0.08 min^-1

(d) 0.09 min^-1

This question was addressed to me in an online quiz.

I'm obligated to ask this question of Chemical Kinetics in division Chemical Kinetics of Chemistry – Class 12

Answer 1

Correct option is (b) 0.06 min^-1

The best explanation: Given, the reaction is 70 percent complete so, a = 70

Time t = 20 minutes

First order integrated rate equation, k = \(\frac{2.303}{t}\)log\(\frac{100}{100-a}\)

k= \(\frac{2.303}{20}\)log\(\frac{100}{100-70}\) = 0.06 min^-1.