Explanation:
The rate constant (k) for a first-order reaction can be calculated using the formula:
k = -ln(A/A₀) / t
where:
A₀ = initial concentration = 0.115 M
A = final concentration = 2.09 × 10^-3 M
t = time = 430 s
Plugging in the values, we get:
k = -ln(2.09 × 10^-3 / 0.115) / 430
= -ln(1.82 × 10^-2) / 430
= 0.0255 s^-1
Therefore, the rate constant for the reaction is 0.0255 s^-1.