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

Answer:

Time required is 50000s

Explanation:

General formula of a second-order reaction is:

$\frac{1}{[A]} =\frac{1}{[A]_0} +Kt$

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:

$\frac{1}{[0.010M]} =\frac{1}{[0.020M]} +1.0x10^{-3}M^{-1}s^{-1}t$

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

Answer:

t = 50,000s

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