Unformatted text preview: 16 Fundamental Concepts Chap. 1 16. A concrete with a density of 2.35 gfcm3 has a hydrogen content of 0.0085 weight fraction. What is the atom density of hydrogen in the concrete? Solution:
From Eq. (1.5), the atom density of hydrogen is (0.0085)(2.35g/cm3)(6.022 x 1023atoms/mol) N(H) = wHpMa = A(H) = 1.20 X 1022 atoms/cm3, 17. How much larger in diameter is a uranium atom compared to an iron atom?
1 gfmol Solution:
From Eq. (1.7) the nuclear diameter is D = 2RoAl/3 so that Du = '~
DPe ) 1/3 1/3 ~ = 1.62. AFe Thus, Du ~ 1.62DFe. By inspecting the chart of the nuclides, determine which element has the most stable isotopes? Solution: The element tin (Sn) has 10 stable isotopes. 19. Find an internet site where the isotopic abundancesof mercury may be found. Solution: http:f fwww.nndc.bnl.gov 20. The earth has a radius of about 6.35 x 106 m and a mass of 5.98 x 1024kg. What would be the radius if the earth had the same mass density as matter in a nucleus? Solution:
Fiomthe text, the density of matter in a nucleusis Pn ~ 2.4 X 1014 /cm3. The g mass of the earth M = P x V where the volume V = {4/3)7rR3. Combining these results and solving for the radius gives R= (~
47fp ) 1/3 = 3(5.98 X 1027 g)
471"(2.4 X 1014 gfcm3) 1/3 = 1.81 X 104 cm = 181 m. July 24, 2002 18. ...
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 Spring '06
 CADY
 Atom, Chemical element, Isotope, Uranium

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