Question

The half life of a 1st order reaction having rate constant k=1.7 x 10-5 sec-1 is
(1) 12.1 hrs
(2) 9.7 hrs
(3) 11.3 hrs
(4) 1.8 hrs​

Answer 1

Answer:

3.11.3 hrs

Explanation:

Given:

k=1.7*10⁻⁵ sec⁻¹

Formula to be used :

$t_1_/_2=ln2/k$

Working:

Since its a first order reaction we know that

$t_1_/_2=ln2/k$

where

ln2=0.693

k=rate constant

$t_1_/_2 = half\>life$

Plugging in the values

$t_1_/_2=0.693/1.7*10^-^5$

=0.4*10⁵ sec

=40760 sec

In hours=40764/3600

=11.32 hours

Therefore the right option is 3.

Hope this helps.