Question

Consider the reaction ALaTeX: \longrightarrow ⟶ Products. The rate law for this reaction is rate = k[A]2 where k=2.90 LaTeX: \times × 10-2 M-1s-1 at a particular temperature. If the initial [A] = 0.0500 M, what is the value of the half-life?

478 s
34.5 s
690. s
23.9 s

Answer 1

Answer: 690 s

Explanation: Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

For a reaction:
`A\rightarrow Products`

`Rate=k[A]^2`

k= rate constant=
`2.90* 10^(-2)`

x = 2= order with respect to A

For a second order reaction,
`t_(1)/(2)=(1)/(k* [A_0])`

`t_{(1)/(2)`= half life = time taken for a reaction to complete to half.

`[A_0]`=initial concentration= 0.0500 M

Thus
`t_{(1)/(2)=(1)/(2.90* 10^(-2)* [0.0500])=690s`