A laboratory rat is exposed to an alpha-radiation source whose activity is 14.3 mCi. (b) The rat has a mass of 385 g and is exposed to the radiation for 14.0 s, absorbing 35% of the emitted alpha particles, each having an energy of 9.12 * 10-13 J. Calculate the absorbed dose in millirads and grays.
Ch.21 - Nuclear Chemistry
Chapter 21, Problem 73
Equation 21.28 is the nuclear reaction responsible for much of the helium-4 production in our Sun. How much energy is released in this reaction?
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Step 1: Identify the nuclear reaction responsible for helium-4 production in the Sun. This is typically the fusion of hydrogen nuclei (protons) into helium-4 through a series of reactions known as the proton-proton chain.
Step 2: Write down the balanced nuclear equation for the proton-proton chain reaction. The overall reaction can be summarized as: 4 \(^1_1\text{H} \rightarrow \ ^4_2\text{He} + 2\beta^+ + 2\nu_e\), where \(^1_1\text{H}\) is a proton, \(^4_2\text{He}\) is a helium-4 nucleus, \(\beta^+\) is a positron, and \(\nu_e\) is a neutrino.
Step 3: Calculate the mass defect, which is the difference between the mass of the reactants and the mass of the products. Use the atomic masses of the hydrogen and helium nuclei to find this difference.
Step 4: Use Einstein's mass-energy equivalence principle, \(E=mc^2\), to calculate the energy released. Here, \(m\) is the mass defect and \(c\) is the speed of light in a vacuum (approximately \(3.00 \times 10^8\) m/s).
Step 5: Convert the energy from joules to a more convenient unit, such as mega-electronvolts (MeV), using the conversion factor \(1 \text{ J} = 6.242 \times 10^{12} \text{ MeV}\).
Related Practice
Textbook Question
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Textbook Question
The table to the right gives the number of protons (p) and neutrons (n) for four isotopes. (a) Write the symbol for each of the isotopes.
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Textbook Question
Radon-222 decays to a stable nucleus by a series of three alpha emissions and two beta emissions. What is the stable nucleus that is formed?
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Textbook Question
Chlorine has two stable nuclides, 35Cl and 37Cl. In contrast, 36Cl is a radioactive nuclide that decays by beta emission. (a) What is the product of decay of 36Cl?
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Textbook Question
Chlorine has two stable nuclides, 35Cl and 37Cl. In contrast, 36Cl is a radioactive nuclide that decays by beta emission. (b) Based on the empirical rules about nuclear stability, explain why the nucleus of 36Cl is less stable than either 35Cl or 37Cl.
Open Question
When two protons fuse in a star, the product is ²H plus a positron. Write the nuclear equation for this process.