Question

5. The rate constant of a first order reaction has been found to
be 0.0435 min ^-1. The initial concentration of the reactant is
0.12 mol L^-1. How much time will it take for the concentration
of the reactant to become 0.03 mol-1
​

Answer 1

Answer:

For a first-order reaction having a rate constant of 0.0435min⁻¹, the time needed to change the concentration of reactant from 0.12mol/L to 0.03mol/L  is 31.87 minutes.

Explanation:

Given that,

        rate constant, k = 0.0435min⁻¹

        initial concentration of reactant, [R]₀ = 0.12mol/L

       concentration of reactant at time t, [R] = 0.03mol/L

For a first-order reaction, time taken t is given by,

           $t=\frac{2.303}{k} log\frac{[R]_0}{[R]}$

⇒           $=\frac{2.303}{0.0435} log\frac{0.12}{0.03} = 31.87 min$

the time taken for the concentration of reactant to become 0.03mol/L from 0.12mol/L is 31.87 minutes.