I need help with question number 3. becomes incorporated into bonés änd dlus TCm
ID: 587199 • Letter: I
Question
I need help with question number 3.
becomes incorporated into bonés änd dlus TCman If a person accidentally ingests 1 g of 90Sr, how muc iu 13 TIcvcl etreted lll h will remain after 40y? displays an average of 47 80s. The (2) Over a period of several days, a sample of 1.00 g of osmium decays per day. These decays are due to the very long-lived radioisotope natural abundance of this isotope is 1.58%. What is the half-life? Express your answer in years. (3) 238 U decays by alpha emission. A natural sample of uranium weighing 0.0532 g pro- duces 651 alpha particles per second. This sample is analyzed by mass spectrom- etry and found to contain 99.2832% 238U and to have an average molar mass of 238.029 229 g mol-1. What is the half-life of 238 U? Express your answer in years.Explanation / Answer
The given Data,
Number of disintegrations per unit time A = 651 alpha particles/sec
mass of U-238 = 0.0532 g *99.2832/100 = 0.05282
Total number of particles in the compound N = 0.05282/238.029229 moles
= 2.219 * 10^-4 * 6.023 * 10^23 atoms
= 1.3365 * 10^20 atoms
we have the formula A = k * N
K = decay constant
and K = 0.693/t1/2
from the above two equations,
A = 0.693/t1/2* N
651 / sec = 0.693/t1/2 * (1.3365 * 10^20)
t1/2 = 1.4227 * 10^17 seconds