Q. A substance having a half-life period of 30 minutes decomposes according to the first order rate law. The fraction decomposed, the balance remaining after 1.5 hours and time for decomposition on its doubling the initial concentration will be.

 2048  236 Chemical Kinetics Report Error

Solution:

We know that
Let the initial concentration of the substance and the substance decomposed in 1.5 hours (90 min) = .t then, Substituting these values in


log

So the fraction decomposed in 1.5 hours
Fraction remaining behind after 1.5 hours .The time required for of decomposition


minutes
Since the reaction is of first order the time required to complete specific fraction is independent of initial concentration (or pressure). Hence of the reaction will decompose in 39.7 mins in this case also.