For a given reaction of first order, it takes 20 minutes for the concentration to drop from 1.0 mol litre-1 to 0.6 mol litre-1. The time required for the concentration to drop from 0.6 mol litre-1 to 0.36 mol litre-1 will be

Question

For a given reaction of first order, it takes 20 minutes for the concentration to drop from 1.0 mol litre-1 to 0.6 mol litre-1. The time required for the concentration to drop from 0.6 mol litre-1 to 0.36 mol litre-1 will be (A) more than 20 minutes (B) less than 20 minutes (C) equal to 20 minutes (D) infinity

Tardigrade Admin · Accepted Answer

(2.303/20) log (1.0/1.0-0.6)=(2.303/t) log (0.6/0.6-0.36) ∴ or (1/20) log 2.5=(1/t) log 2.5 ∴ t=20 minutes

Q. For a given reaction of first order, it takes 20 minutes for the concentration to drop from $1.0 m o ll i t r e^{- 1}$ to $0.6 m o l l i t r e^{- 1}$ . The time required for the concentration to drop from $0.6 m o l l i t r e^{- 1}$ to $0.36 m o l l i t r e^{- 1}$ will be

more than 20 minutes

less than 20 minutes

equal to 20 minutes

infinity

$\frac{2.303}{20}$ log $\frac{1.0}{1.0 - 0.6} = \frac{2.303}{t}$ log $\frac{0.6}{0.6 - 0.36}$
$∴ or \frac{1}{20}$ log $2.5 = \frac{1}{t}$ log $2.5$
$∴ t = 20$ minutes

Q. For a given reaction of first order, it takes 20 minutes for the concentration to drop from 1.0mollitre−1 to 0.6mollitre−1. The time required for the concentration to drop from 0.6mollitre−1 to 0.36mollitre−1 will be