The integrated rate law allows chemists to predict the reactant concentration af

Question

The integrated rate law allows chemists to predict the reactant concentration after a certain amount of time, or the time it would take for a certain concentration to be reached.

The integrated rate law for a first-order reaction is:
[A]=[A]0ekt

Now say we are particularly interested in the time it would take for the concentration to become one-half of its initial value. Then we could substitute [A]02 for [A] and rearrange the equation to:
t1/2=0.693k
This equation calculates the time required for the reactant concentration to drop to half its initial value. In other words, it calculates the half-life.

Half-life equation for first-order reactions:
t1/2=0.693k
where t1/2 is the half-life in seconds (s), and k is the rate constant in inverse seconds (s1).

I got part A

Correct

Significant Figures Feedback: Your answer 1194.83s was either rounded differently or used a different number of significant figures than required for this part.

Part B

What is the rate constant of a first-order reaction that takes 262 seconds for the reactant concentration to drop to half of its initial value?

Express your answer with the appropriate units.

I need part B

Explanation / Answer

k = 0.693/t1/2

t1/2 = 262 seconds

k = 0.693/262 = 0.002645 s-1

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