Please help with this chemistry II question.?

H

Hayley

New member
Consider two reaction vessels, one containing A and the other containing B. At t = 0, [A]o = o. A and B decompose by first order kinetics with rate constants of
kA = 4.50 × 10-4 s-1 and kB = 3.70 × 10-3 s-1, respectively. Calculate the time that must pass to reach the condition such that [A] = (4.19).
 
Since:
A = Ao*e^(-kAt)
B = Bo*e^(-kBt)

A=4.19B becomes:
Ao*e^(-kAt) = 4.19 * Bo*e^(-kBt)

since Ao=Bo, we can cancel them out:

e^(-kAt) = 4.19 e^(-kBt)
ln[e^(-kAt)]=ln[4.19e^(-kBt)]
-kAt=ln4.19-kBt

plug in the k's and use your calculator to find t
 
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