The rate constant, k, for the first order reaction A --> 2B is 0.0424 s-1. If the initial concentration is 2.14M, what is the concentration after 56.114 seconds?
Answer-
Given,
Rate Constant = 0.0424 s-1
Initial Concentration = 2.14 M
Time = 56.114 s
Concentration at given time = ?
We know that,

where,
A = Concentration at time, t
A
= Initial
Concentration
k = rate constant
t = time
Put all the values,

[A] = 2.14 * e-(0.0424 * 56.114)
[A] = 2.14 * e-2.38
[A] = 2.14 * 0.0925
[A] = 0.19795 M
So, the concentration after 56.114 seconds is 0.198 M.
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