A first order reaction is half completed in 45 min. How long does it need 99.9 % of the reaction to be completed?

Question

A first order reaction is half completed in 45 min. How long does it need 99.9 % of the reaction to be completed? (A) 10 Hours (B) 20 Hours (C) 5 Hours (D) 7.5 Hours

Tardigrade Admin · Accepted Answer

t 99.9 %=10 t 50 % =10 × 45 min =450 min =7.5 hours

Q. A first order reaction is half completed in $45$ min. How long does it need $99.9%$ of the reaction to be completed?

10 Hours

20 Hours

5 Hours

7.5 Hours

$t_{99.9%} = 10 t_{50%}$
$= 10 \times 45 min = 450 min = 7.5$ hours

Q. A first order reaction is half completed in 45 min. How long does it need 99.9% of the reaction to be completed?