.11 Sprint 8:05 PM session.masteringchemistry.com , Post-Lecture Ch 14 Haillfe (

Question

.11 Sprint 8:05 PM session.masteringchemistry.com , Post-Lecture Ch 14 Haillfe (kinetics) for First Order Reactions 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-Aloe 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 for A] and rearrange the equation to: This equation calculates the time required for the reactant concentration to drop to half its nitial value. In other words, it calculates the half-life for first-order reactions: 1/2 where ty/2 is the half-ife in seconds (s), and k is the rate constant in inverse seconds Part A What is the half-life of a first-order reaction with a rate constant of 7.90x104 s-12 Express your answer with the appropriate units View Available Hint(s) Valuc Units -Part B What is the rate constant of a first-order reaction that takes 506 seconds for the reactant concentration to drop to half of its initial value? Express your answer with the View Available Hint(s) units. Value Units - Part C

Explanation / Answer

part A

Given

k = 7.90 * 10-4 s-1

t1/2 = 0.693 / k = 0.693 / 7.90 * 10-4 s-1 = 877.215 s Answer

Part B

Given

t1/2 = 506 s = 0.693 / k

k = 1.3696 * 10-3 s-1 answer

Part C

Given

[A] = [A]o e-kt

given

[A] / [A]o = 1/8

k = 7.1 * 10-3 s-1

1/8 = e^(- 7.1 * 10-3 s-1 * t )

2.07944 = 7.1 * 10-3 s-1 * t   

t = 292.288 s Answer

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.