Answer:
Initial concentration = 2.30 M
Explanation:
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Full Question;
For this question, consider the reaction A-->B with a rate constant k=7.17x10^-4 m/s.
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From the units of the rate constant, we can tell that this is a Zero order reaction.
k = 7.17 x 10^-4 m/s
t = 15 minutes = 15 * 60 = 600s (Converting to seconds)
concentration of A to decrease by 28%.
[A] = Final Concentration
[A]o = Initial Concentration
[A] = [A]o - ( [A]o * 28 ) / 100
[A] = [A]o - 0.28[A]o
[A] = 0.72 [A]o
For a zero order reaction, we have;
[A] = [A]o -kt
Substituting the new value of [A], we have;
0.72 [A]o = [A]o - (7.17 x 10^-4 * 900)
0.28 [A]o = (7.17 x 10^-4 * 900)
[A]o = 2.30 M
