This is a Numeric Entry question/ It is worth 1 point /You have unlimited attemp

Question

This is a Numeric Entry question/ It is worth 1 point /You have unlimited attempts/There is no attempt penalty 09 Question (1 point) See page 646 Until roughly 1970, tritium (3H), a radioactive isotope of hydrogen, was a component of fluorescent watch dials and hands. For 3H, tu2-12.3 yr 1st attempt See Periodic Table Q See Hint Assume you have such a watch. If a minimum of 16.0% of the original tritium is needed to read the dial in dark places, for how many years could you read the time at night? Assume first-order kinetics. yr

Explanation / Answer

Given:
Half life = 12.3 yr
use relation between rate constant and half life of 1st order reaction

k = (ln 2) / k
= 0.693/(half life)
= 0.693/(12.3)
= 5.634*10^-2 yr-1

we have:
[3H]o = 100 (Let initial concentration be 100)
[3H] = 16 (16 % is remaining)
k = 5.634*10^-2 yr-1

use integrated rate law for 1st order reaction
ln[3H] = ln[3H]o - k*t
ln(16) = ln(100) - 5.634*10^-2*t
2.7726 = 4.6052 - 5.634*10^-2*t
5.634*10^-2*t = 1.8326
t = 32.5 yr
Answer: 32.5 yr

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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