Answer:
Rate constant = 0.01238 days⁻¹
Explanation:
The first order reaction has as general equation:
Ln[A] = -kt + Ln[A]₀
Where [A] is concentration of the reactant after time t,
k is rate constant
And [A]₀ the initial concentration of the reactant
The half-life is the time required to reach the half of the initial concentration. If [A]₀ = 1; [A] = 1/2
Replacing:
Ln[1/2] = -kt + Ln[1]
-0.693 = -k*56days
0.01238days⁻¹ = k