For a first-order reaction, the half-life period is independent of the (A) initial concentration.
The half-life of a reaction is defined as the time it takes for the concentration of the reactant to decrease by half. In a first-order reaction, the rate of the reaction is proportional to the concentration of the reactant, so the rate equation can be written as:
Rate = k[A]
Where [A] is the concentration of the reactant at any given time, and k is the rate constant.
The integrated rate equation for a first-order reaction is:
ln([A]₀/[A]) = kt
Where [A]₀ is the initial concentration of the reactant, [A] is the concentration of the reactant at time t, and k is the rate constant.
The half-life (t₁/₂) is the time it takes for [A] to decrease to half its initial concentration [A]₀. We can substitute these values into the integrated rate equation:
ln([A]₀/([A]₀/2)) = k(t₁/₂)
Simplifying:
ln(2) = k(t₁/₂)
From this equation, we can see that the half-life (t₁/₂) is only dependent on the rate constant (k) for a first-order reaction. It is independent of the initial concentration [A]₀ or any other power or root of the concentration. Therefore, the correct answer is (A) initial concentration.