Question

For a first order reaction , `A to` Products, the concentrations of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is:
A. `1.73 xx 10^(-5)` M/min
B. `3.47 xx 10^(-4) M//min`
C. `3.47 xx 10^(-5)M//min`
D. `1.73 xx 10^(-4) M//min`

Answer 1

Correct Answer - B
b) `k=2.303/t log ([A]_(0))/([A])`
`=2.303/(40"min") log (0.1M)/(0.025 M)`
rate = `k[A]_(0)= 0.0347 min^(-1)(0.01M)`
`=3.47 xx 10^(-4) M min^(-1)`