Question

What time does it take for reactants to reduce to 3/4 of initial concentration if the rate constant is 7.5 x 10^-3 s^-1?

(a) 38.4s

(b) 40.2s

(c) 39.3s

(d) 36.8s

This question was posed to me in final exam.

I would like to ask this question from Chemical Kinetics in chapter Chemical Kinetics of Chemistry – Class 12

Answer 1

Correct choice is (a) 38.4s

To explain: Given,

K=7.5 x 10^-3 s^-1

K = (2.303/t) x log([R]0/[R])

t = (2.303/7.5 x 10^-3) x log([100]/[25])

t = (2.303/7.5 x 10^-3) x 0.6

t = 38.4s.