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- When a positron and an electron annihilate one another, the resulting mass is completely converted to energy. Calculate the energy associated with this process in kJ/mol.
Problem 87
Problem 88
A typical nuclear reactor produces about 1.0 MW of power per day. What is the minimum rate of mass loss required to produce this much energy?
Problem 89
Find the binding energy in an atom of 3He, which has a mass of 3.016030 amu.
Problem 91
The nuclide 247Es can be made by bombardment of 238U in a reaction that emits five neutrons. Identify the bombarding particle.
Problem 92
The nuclide 6Li reacts with 2H to form two identical particles. Identify the particles.
Problem 93
The half-life of 238U is 4.5⨉109 yr. A sample of rock of mass 1.6 g produces 29 dis/s. Assuming all the radioactivity is due to 238U, find the percent by mass of 238U in the rock.
Problem 94
The half-life of 232Th is 1.4⨉1010 yr. Find the number of disintegrations per hour emitted by 1.0 mol of 232Th.
- 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?
Problem 95
Problem 96
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.)
- 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?
Problem 97
Problem 98
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.
Problem 99
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.
Problem 100
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.