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Ch.20 - Radioactivity and Nuclear Chemistry
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoTro 4th EditionCh.20 - Radioactivity and Nuclear ChemistryProblema 76
Capitolo 20, Problema 76

Suppose a patient is given 1.55 mg of I-131, a beta emitter with a half-life of 8.0 days. Assuming that none of the I-131 is eliminated from the person's body in the first 4.0 hours of treatment, what is the exposure (in Ci) during those first four hours?

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1
Convert the mass of I-131 from milligrams to grams by using the conversion factor: 1 mg = 0.001 g.
Calculate the number of moles of I-131 using its molar mass (approximately 130.91 g/mol).
Determine the number of atoms of I-131 using Avogadro's number (6.022 x 10^23 atoms/mol).
Use the decay constant formula, \( \lambda = \frac{0.693}{t_{1/2}} \), where \( t_{1/2} \) is the half-life in days, to find the decay constant in terms of hours.
Calculate the activity in curies (Ci) using the formula \( A = \lambda N \), where \( N \) is the number of atoms, and convert the result from disintegrations per second to curies using the conversion factor: 1 Ci = 3.7 x 10^10 disintegrations per second.

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Radioactive Decay

Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation. This decay occurs at a predictable rate characterized by the half-life, which is the time required for half of the radioactive substance to decay. Understanding this concept is crucial for calculating the remaining quantity of a radioactive isotope over time.
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Rate of Radioactive Decay

Half-Life

Half-life is a specific time period in which half of a given amount of a radioactive substance will decay. For I-131, the half-life is 8.0 days, meaning that after 8.0 days, only 50% of the original amount will remain. This concept is essential for determining how much of the substance is present at any given time, especially in the context of medical treatments.
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Zero-Order Half-life

Curie (Ci)

The Curie (Ci) is a unit of radioactivity that measures the rate of decay of radioactive material. One Curie is defined as 3.7 x 10^10 disintegrations per second. In the context of medical treatments, understanding the exposure in Ci helps quantify the amount of radiation a patient is receiving, which is critical for assessing safety and efficacy.
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Units of Radiation Measurement
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a. 2713Al + 42He → 3015P + ____

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Domanda del libro di testo

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Complete each nuclear equation and calculate the energy change (in J/mol of reactant) associated with each (Be-9 = 9.012182 amu, Bi-209 = 208.980384 amu, He-4 = 4.002603 amu, Li-6 = 6.015122 amu, Ni-64 = 63.927969 amu, Rg-272 = 272.1535 amu, Ta-179 = 178.94593 amu, and W-179 = 178.94707 amu). a. _____ + 94Be → 63Li + 42He

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