{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

HW6-18

# HW6-18 - 5-13 18 The averagemass of potassium in the human...

This preview shows page 1. Sign up to view the full content.

5-13 18. The average mass of potassium in the human body is about 140 g. From the abundance and half-life of 40K (see Table 5.2), estimate the average activity (Bq) of 40K in the body. Solution: From Table 5.2, the atomic abundance of40K is 140 = 0.000117. The number of potassium atoms in the body N K is N K = ~ = .(140)(6.022 X 1023) = 2.156 X 1024 atoms. 39.0983 The number of 4oK atoms is N40 = 0.000117NK = 2.523 X 1020 atoms. This number of 4oK atoms has an activity A40 = A40N40. The decay constant for 40K is In2 A40 = - T = 1.73 X 10-17 S-1 1/2 Thus the 40K activity in the body is A40 = A40N40 = (1.73 x 10-17)(2.523 x 1020) = 4,360 Bq. 19. The naturally occurring radionuclides 222Rn and 220Rndecay by emitting a particles which have a range of only a few centimeters in air. Yet there is con- siderable concern about the presence of these radioisotopes in interior spaces. Explain how these radioisotopesenter homes and workspaces and why they are
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern