A first order reaction is `20%` complete in `10 min`. Calculate (a) the specific rate constant of the reaction and (b) the time taken for the reaction to reach `75%` completion.

Explanation

(i) `k=0.023" min"^(-1)`, (ii) 60 min For a first order reaction,
`kt =" In "([A]_(o))/([A])`
Where `[A]_(o)` = Initial concentration of reactant [A] = Concentration of reactant remaining unreacted at time t
(i) `k=(1)/(t)" In "([A]_(o))/([A])=(1)/(10)" In "(100)/(100-20) =(1)/(10)" In "(5)/(4) =(2.303 (log 5-2 log 2))/(10)"m in"^(-1) =0.023" m in"^(-1)`
(ii) `t=(1)/(k)" In "(100)/(25) =(2" In "2)/(k) =(2xx0.693)/(0.023) =60` m in