Question

In a first order reaction the concentration of reactants decreases from 400mol L^-1 to 25 mol L^-1 in 200 seconds. The rate constant for the reaction is ______.

Options

• 1.01386 S^-1

• 2 × 10 S^-1

• 1.386 × 10^-2 S^-1

• 3.4 × 10 S^-1

Answer 1

In a first order reaction the concentration of reactants decreases from 400mol L^-1 to 25 mol L^-1 in 200 seconds. The rate constant for the reaction is 1.386 × 10^-2 S^-1.

Explanation:

K = `2.303/"t" log  "R"_"o"/"R"`

K = `2.303/200 log  400/25`

= 0.01386 s^-1 

= 1.386 × 10^-2 S^-1