Open Question
A 1.50-L gas sample at 745 mm Hg and 25.0 °C contains 3.55% radon-220 by volume. Radon-220 is an alpha emitter with a half-life of 55.6 s. How many alpha particles are emitted by the gas sample in 5.00 minutes?
Ch.20 - Radioactivity and Nuclear Chemistry
Chapter 20, Problem 96
The half-life of 235U, an alpha emitter, is 7.1⨉108 years. Calculate the number of alpha particles emitted by 1.0 mg of this nuclide in 1.0 minute.
Verified step by step guidance1
<Determine the number of moles of 235U in 1.0 mg. Use the molar mass of 235U, which is approximately 235 g/mol.>
<Calculate the number of atoms of 235U using Avogadro's number (6.022 × 10^23 atoms/mol).>
<Use the half-life formula to find the decay constant (k) for 235U: k = \frac{\ln(2)}{\text{half-life}}.>
<Calculate the number of decays (and thus alpha particles emitted) in 1.0 minute using the formula: N = N_0 (1 - e^{-kt}), where N_0 is the initial number of atoms and t is the time in minutes.>
<Convert the time from minutes to years if necessary, and solve for the number of alpha particles emitted.>
Related Practice
Open Question
A 228-mL sample of an aqueous solution contains 2.35% MgCl2 by mass. Exactly one-half of the magnesium ions are Mg-28, a beta emitter with a half-life of 21 hours. What is the decay rate of Mg-28 in the solution after 4.00 days? (Assume a density of 1.02 g/mL for the solution.)
Open Question
When a positron and an electron collide and annihilate each other, two photons of equal energy are produced. What is the wavelength of these photons?
Open Question
Given that the energy released in the fusion of two deuterons to a 3He and a neutron is 3.3 MeV, and in the fusion to tritium and a proton it is 4.0 MeV, calculate the energy change for the process 3He + 1n → 3H + 1p. Suggest an explanation for why this process occurs at much lower temperatures than either of the first two.
Textbook Question
The nuclide 18F decays by both electron capture and β+ decay. Find the difference in the energy released by these two processes. The atomic masses are 18F = 18.000950 and 18O = 17.9991598.
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