Question

A first order reaction has specific rate constant of `10^(-3)s^(-1)`. How much time will it take for 10g to reduce to half the quantity (i.e. 5g) ?

Answer 1

According to available data:
`a=10.0g, a-x = 5.0 g, k=10^(-3)s^(-1)`
For first order reaction,
`(2.303)/t log (a)/(a-x) = (2.303)/(10^(-3)s^(-1)) xx log 10/5=(2.303)/(10^(-3)s^(-1))log2`
`=(2.303 xx 0.3010)/(10^(-3)s^(-1)) = (0.693)/(10^(-3)s^(-1)) = 693s`