Q.

An organic compound undergoes first order decomposition. If the time taken for the 60% decomposition is 540 s, then the time required for 90% decomposition will be is ______ s. (Nearest integer).

(Given: ln 10 = 2.3; log 2 = 0.3)                           [2023]


Ans.

(1350)

First order reaction

t=1klnC0Ct

540=1kln10040                        ...(1)

t=1kln10010                             ...(2)

From (1) and (2)

540t=ln10040ln10010=log100-log40log100-log10

540t=2-1.62-1=0.4

t=5400.4=1350 s