The half-life period of a first order chemical reaction is 6.93 minutes.
The time required for 99% completion of reaction will be (log 2 = 0.301)
46.06 min
k=0.693t12 (first order)
=0.6936.93=0.1 min−1
Now, for first order reaction,
[A]=[A]0 e−kt→ kt
=2.303 log [A]o[A]
Now,kt=2.303 log [A]o[A].100
⇒ kt=2.303 log [100]
⇒kt=2.303×2⇒t=4.606k
⇒t=4.6060.1=46.06 min