d. The U.S. Environmental Protection Agency (EPA) recom- mends that 222Rn levels not exceed 4 pCi per liter of air (
1 1012 Ci 1 Ci 1 curie 3.7 1010
decay events per second; 1 pCi ). Convert 4.0 pCi per liter of air into concentra-
tions units of 222Rn atoms per liter of air and moles of 222Rn per liter of air.
67. To determine the Ksp value of Hg2I2, a chemist obtained a solid sample of Hg2I2 in which some of the iodine is present as ra- dioactive 131I. The count rate of the Hg2I2 sample is counts per minute per mole of I. An excess amount of Hg2I2(s) is placed into some water, and the solid is allowed to come to equi-
librium with its respective ions. A 150.0-mL sample of the satu- rated solution is withdrawn and the radioactivity measured at 33
counts per minute. From this information, calculate the Ksp value for Hg2I2.
68. Estimate the temperature needed to achieve the fusion of deu- terium to make an alpha particle. The energy required can be estimated from Coulomb’s law [use the form (Q1Q2 r), using
E 9.0 109 1015 Q 1.6 1019 C for a proton, and r 2 m for the helium nucleus; the unit for the proportionality
constant in Coloumb’s law is J mC2. ] Integrative Problems
These problems require the integration of multiple concepts to find the solutions.
69. A recently reported synthesis of the transuranium element bohrium (Bh) involved the bombardment of berkelium-249 with
neon-22 to produce bohrium-267. Write a nuclear reaction for this synthesis. The half-life of bohrium-267 is 15.0 seconds. If 199 atoms of bohrium-267 could be synthesized, how much time would elapse before only 11 atoms of bohrium-267 remain? What is the expected electron configuration of elemental bohrium?
70. Radioactive cobalt-60 is used to study defects in vitamin B12 ab- sorption because cobalt is the metallic atom at the center of the
vitamin B12 molecule. The nuclear synthesis of this cobalt isotope involves a three-step process. The overall reaction is iron-58
1H 1.00782 amu
reacting with two neutrons to produce cobalt-60 along with the emission of another particle. What particle is emitted in this nuclear synthesis? What is the binding energy in J per nucleon for the cobalt-60 nucleus (atomic masses: ). What is the de Broglie wavelength of the
emitted particle if it has a velocity equal to 0.90c where c is the speed of light?
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