In a first order reaction, 10% of the reactant is consumed in 25 minutes. Calculate :
The time required for completing 87.5% of the reaction.

Explanation

For a first order reaction,
` k= ( 2.303 )/(t) log "" (a)/((a-x))`
`=(2.303)/( t) log ""(100)/((100-10)) = 4.215 xx 10^(-3) min""^(-1)`
`t=(2.303)/(k) log "" (a)/((a-x))`
`=( 2.303 )/( 4.215 xx 10^(-3)) log "" (100)/( ( 100-87.5 )) = 493.38 min`