help me MasteringChemistry: Post Lecture Homework Chapter 17- Google Chrome Secu

Question

help me

MasteringChemistry: Post Lecture Homework Chapter 17- Google Chrome Secure https://session.masteringchemistry.com/myct/itemView?assignmentProblemID-93468599 ost Lecture Homework Chapter 17 Exercise 17.70 Resources a previous | 9 of 21 | n Exercise 17.70 Part A lodine-131 is often used in nuclear medicine to obtain images of the thyroid If you start with 8.5x1010 I- 131 atoms, how many are left after approximately 1month? I- 131 has a half-life of 8.0 days. Express your answer using two significant figures. atoms Submit My Answers Give Up Provide Feedback Continue

Explanation / Answer

A half-life of 8 days means that every 8 days the half of the amount of I-131 decay...
So if you start with 8.5x10^10 atoms and you consider 32 days in a month (question says "approximately") your amount of atoms goes through 4 half-lives.
Then
8.5*10^10/ 2 = 4.25x10^10 atoms after 8 days=1 half-life
4.25x10^10 / 2 = 2.125*10^10 atoms after 16 days = 2 half-lives
2.125*10^10/ 2 = 1.06*10^10atoms after 24 days = 3 half-lives
1.06*10^10 / 2 = 5.3 * 10^9 atoms after 32 days = 4 half-lives
So 5.3x10^9 atoms is the answer.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

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