Skip to main content
Ch.21 - Nuclear Chemistry
Chapter 21, Problem 52

Based on the following atomic mass values: 1H, 1.00782 amu; 2H, 2.01410 amu; 3H, 3.01605 amu; 3He, 3.01603 amu; 4He, 4.00260 amu—and the mass of the neutron given in the text, calculate the energy released per mole in each of the following nuclear reactions, all of which are possibilities for a controlled fusion process:
(a) 21H + 31H → 42He + 10n
(b) 21H + 21H → 32He + 10n
(c) 21H + 32He → 42He + 11H

Verified step by step guidance
1
Step 1: Identify the reactants and products in the nuclear reaction. In this case, the reactants are two 2H (deuterium) atoms and the products are one 3He (Helium-3) atom and one neutron (1n).
Step 2: Calculate the total mass of the reactants by adding the atomic masses of the two 2H atoms. Use the given atomic mass values.
Step 3: Calculate the total mass of the products by adding the atomic mass of the 3He atom and the mass of the neutron. Use the given atomic mass values.
Step 4: Calculate the mass difference between the reactants and the products by subtracting the total mass of the products from the total mass of the reactants. This mass difference is the mass that has been converted into energy during the nuclear reaction.
Step 5: Convert this mass difference into energy using Einstein's mass-energy equivalence principle, E=mc^2, where E is the energy, m is the mass, and c is the speed of light. Multiply the mass difference by c^2 to get the energy released per reaction. To get the energy released per mole of reactions, multiply this energy by Avogadro's number (6.022 x 10^23).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
10m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nuclear Fusion

Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus, releasing energy in the process. This reaction occurs under extreme conditions of temperature and pressure, typically found in stars. The energy released is a result of the mass defect, where the mass of the resulting nucleus is less than the sum of the original masses, according to Einstein's equation E=mc².
Recommended video:
Guided course
02:06
Nuclear Binding Energy

Mass Defect

The mass defect refers to the difference between the mass of an atomic nucleus and the sum of the masses of its individual protons and neutrons. This discrepancy arises because some mass is converted into energy during the formation of the nucleus. Understanding mass defect is crucial for calculating the energy released in nuclear reactions, as it directly relates to the binding energy of the nucleus.
Recommended video:
Guided course
00:55
Calculating Mass Defect

Energy Calculation in Nuclear Reactions

To calculate the energy released in nuclear reactions, one must first determine the mass defect by subtracting the total mass of the reactants from the total mass of the products. This mass defect is then converted into energy using Einstein's equation E=mc². The energy calculated is typically expressed in joules or kilojoules per mole, allowing for comparisons between different reactions and their feasibility for energy production.
Recommended video:
Guided course
02:06
Nuclear Binding Energy
Related Practice
Textbook Question

The atomic masses of hydrogen-2 (deuterium), helium-4, and lithium-6 are 2.014102 amu, 4.002602 amu, and 6.0151228 amu, respectively. For each isotope, calculate

(c) the nuclear binding energy per nucleon.

95
views
Textbook Question

The atomic masses of nitrogen-14, titanium-48, and xenon-129 are 13.999234 amu, 47.935878 amu, and 128.904779 amu, respectively. For each isotope, calculate (a) the nuclear mass.

653
views
Open Question
The energy from solar radiation falling on Earth is 1.07 * 10^16 kJ/min. (a) How much loss of mass from the Sun occurs in one day from just the energy falling on Earth? (b) If the energy released in the reaction 235U + 10n → 14156Ba + 9236Kr + 310n (235U nuclear mass, 234.9935 amu; 141Ba nuclear mass, 140.8833 amu; 92Kr nuclear mass, 91.9021 amu) is taken as typical of that occurring in a nuclear reactor, what mass of uranium-235 is required to equal 0.10% of the solar energy that falls on Earth in 1.0 day?
Open Question
The isotope 6228Ni has the largest binding energy per nucleon of any isotope. Calculate this value from the atomic mass of nickel-62 (61.928345 amu) and compare it with the value given for iron-56 in Table 21.7.
Open Question
Iodine-131 is a convenient radioisotope to monitor thyroid activity in humans. It is a beta emitter with a half-life of 8.02 days. The thyroid is the only gland in the body that uses iodine. A person undergoing a test of thyroid activity drinks a solution of NaI, in which only a small fraction of the iodide is radioactive. (a) Why is NaI a good choice for the source of iodine? (b) If a Geiger counter is placed near the person’s thyroid (which is near the neck) right after the sodium iodide solution is taken, what will the data look like as a function of time?
Textbook Question

Iodine-131 is a convenient radioisotope to monitor thyroid activity in humans. It is a beta emitter with a half-life of 8.02 days. The thyroid is the only gland in the body that uses iodine. A person undergoing a test of thyroid activity drinks a solution of NaI, in which only a small fraction of the iodide is radioactive. (c) A normal thyroid will take up about 12% of the ingested iodide in a few hours. How long will it take for the radioactive iodide taken up and held by the thyroid to decay to 0.01% of the original amount?

890
views