A first order reaction has a specific reaction rate of `10^(-3) s^(-1)`. How much time will it take for `10 g` of the reactant to reduce to `2.5 g`. (Given `log4 = 0.6021`).

Explanation

According to available data:
a=10g, `(a-x)=2.5 g, k=10^(-3)s^(-1)`
for first order reaction,
`t=(2.303)/k log a/(a-x) = 2.303/(10^(-3)s^(-1))log 10/(2.5)`
`=(2.303)/(10^(-3)s^(-1))log 4 = 2.303 xx 0.6020 xx 10^(3)`s
`=1.3864 xx 10^(3)=(1.3864 xx 1000)/(60) = 23.11 min`