For first order reaction
k=t210.693
[A]=4[B]
[A]0e−kAt=4[B]0e−kBt
∵ as [A]0=[B]0;e−kAt=4e−kBt
−kAt=ln4−kBt
∴t(kB−kA)=2ln2
t=(500.693−1000.693)2×0.693=2−12×100=200sec
A flask is filled with equal moles of A and B. The half lives of A and B are 100s and 50s respectively and are independent of the initial concentration. The time required for the concentration of A to be four times that of B is____s.
(Given : ln2=0.693)
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