Question

A second-order reaction starts with an initial concentration of 0.020 M of the reactant. If the rate constant is 1.0x10-3 M-1s-1, what is the time required for the concentration of the reactant to reach 0.010 M?

Answer 1

Time required is 50000s

Step-by-step explanation:

General formula of a second-order reaction is:

`(1)/([A]) =(1)/([A]_0) +Kt`

Where [A] is concentration of reactant after time t passed, [A]₀ is initial concentration of reactant and K is rate constant of reaction.

Replacing:

`(1)/([0.010M]) =(1)/([0.020M]) +1.0x10^(-3)M^(-1)s^(-1)t`

50M⁻¹ = 1.0x10⁻³M⁻¹s⁻¹ t

50000s = t

Thus, after 50000s, the reactant concentration decrease from 0.020M to 0.010M

Answer 2

t = 50,000s

Step-by-step explanation:

Reaction is second order.

Initial conc. [A]o = 0.020 M

Rate constant = 1.0x10-3 M-1s-1

Final conc. [A] = 0.010M

Time = ?

1 / [A] = kt + 1 / [A]o

Substituting the values;

1 / 0.010 = 1.0x10-3 * t + (1/0.020)

100 - 50 = 1.0x10-3 * t

t = 50 / (1.0x10-3)

t = 50,000s