Question

The Half Life period of a first order process is 1.6 minutes it will be 90% complete in?​

Answer 1

Answer : The time for 90% completion reaction will be, 5.33 minutes.

Solution :  

As we know that the radioactive decay follow the first order kinetics.

Formula used :

$\frac{N}N_o}=(\frac{1}{2})^{\frac{t}{t_{1/2}}}$

by taking 'log' on both side, we get

$\log (\frac{N}{N_o})=\frac{t}{t_{1/2}}\times \log (\frac{1}{2})$

where,

N = amount left after decay process = 100 - 90 = 10

$N_o$ = initial amount = 100

t = time for 90% completion reaction = ?

$t_{1/2}$ = half life = 1.6 minutes

Now put all the given values in this formula, we get the time for 90% completion reaction.

$\log (\frac{10}{100})=\frac{t}{1.6min}\times \log (\frac{1}{2})$

$t=5.33min$

Therefore, the time for 90% completion reaction will be, 5.33 minutes.