Problem 51 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is a fusion reaction? (a) \({ }_{\text {os }} \mathrm{U}^{235}+{ }_{0} \mathrm{n}^{1} \longrightarrow{ }_{56} \mathrm{Ba}^{141}+{ }_{36} \mathrm{Kr}^{92}+3_{0} \mathrm{n}^{1}\) (b) \({ }_{92} \mathrm{Fe}^{219}+{ }_{0} \mathrm{n}^{1} \longrightarrow{ }_{92} \mathrm{U}^{239}+\mathrm{Y}\) (c) \({ }_{26} \mathrm{Fe}^{55}+{ }_{-1} \mathrm{e}^{0} \longrightarrow{ }_{25} \mathrm{Mn}^{55}\) (d) \({ }_{1} \mathrm{H}^{1}+{ }_{1} \mathrm{H}^{1}+2 \underset{0} \mathrm{n}^{1} \longrightarrow{ }_{2} \mathrm{He}^{4}+\) energy

Step-by-Step Solution

Answer

Reaction (d) is a fusion reaction.

Step 1: Understanding Fusion Reactions

Fusion reactions involve two or more light nuclei coming together to form a heavier nucleus. This process releases energy and usually involves simple elements like Hydrogen isotopes fusing to form Helium.

Step 2: Analyzing Reaction (a)

Reaction (a) describes the splitting of a Uranium nucleus into smaller parts: \[ \underline{\phantom{xxx}}_{92}^{235}\mathrm{U} + \underline{\phantom{xxx}}_{0}^{1}\mathrm{n} \rightarrow \underline{\phantom{xxx}}_{56}^{141}\mathrm{Ba} + \underline{\phantom{xxx}}_{36}^{92}\mathrm{Kr} + 3\underline{\phantom{xxx}}_{0}^{1}\mathrm{n} \] This process is a fission reaction, not fusion, as the original nucleus splits apart.

Step 3: Investigating Reaction (b)

Reaction (b) also doesn't fit the fusion criteria: \[ \underline{\phantom{xxx}}_{92}^{219}\mathrm{Fe} + \underline{\phantom{xxx}}_{0}^{1}\mathrm{n} \rightarrow \underline{\phantom{xxx}}_{92}^{239}\mathrm{U} + Y \] This is an example of neutron capture where a neutron causes a change in an atomic number or mass, potentially part of transmutation processes, but not fusion.

Step 4: Reviewing Reaction (c)

Reaction (c) shows a beta decay process: \[ \underline{\phantom{xxx}}_{26}^{55}\mathrm{Fe} + \underline{\phantom{xxx}}_{-1}^{0}\mathrm{e} \rightarrow \underline{\phantom{xxx}}_{25}^{55}\mathrm{Mn} \] Beta decay is a type of radioactive decay and doesn't fit the criteria for a fusion reaction.

Step 5: Recognizing Fusion in Reaction (d)

In reaction (d): \[ \underline{\phantom{xxx}}_{1}^{1}\mathrm{H} + \underline{\phantom{xxx}}_{1}^{1}\mathrm{H} + 2\underline{\phantom{xxx}}_{0}^{1}\mathrm{n} \rightarrow \underline{\phantom{xxx}}_{2}^{4}\mathrm{He} + \text{energy} \]Two hydrogen isotopes combine to form a helium nucleus, with the release of energy, which is the typical characteristic of a fusion reaction.

Key Concepts

Nuclear Reactions

Nuclear reactions are processes that change the composition, energy, or structure of an atomic nucleus. These reactions are distinct from chemical reactions, which involve interactions between electrons surrounding an atom. In nuclear reactions, the strong nuclear force plays a key role in determining the behavior and outcome of the reaction.
The key characteristics of nuclear reactions include:

• Involvement of atomic nuclei rather than electrons
• Release or absorption of a significant amount of energy
• Potential transformation of elements into other elements

The main types of nuclear reactions are fission and fusion. Both of these processes have profound applications in energy production, medical treatments, and scientific research. Understanding nuclear reactions is crucial for developments in nuclear physics and technology.

Fission vs Fusion

Fission and fusion are the two main types of nuclear reactions, each with unique properties and applications. Fusion reactions involve the merging of two or more light nuclei to form a heavier nucleus, often resulting in the release of vast amounts of energy. This is commonly observed in stars, including the sun, where hydrogen nuclei fuse to form helium.

• Fusion: Light nuclei combine to form a heavier nucleus, releasing energy.
• Fission: A heavy nucleus splits into smaller nuclei, also releasing energy.

Fission, on the other hand, involves the splitting of a heavy nucleus into smaller parts along with the release of energy. This process is commonly used in nuclear power plants and atomic bombs. While both processes release energy, fusion is often considered a cleaner and more sustainable source of energy, as it produces minimal radioactive waste compared to fission. However, achieving and maintaining the conditions necessary for fusion on Earth is technologically challenging.

Nuclear Physics

Nuclear physics is the field of physics that studies atomic nuclei and their interactions. It deals with understanding the fundamental components of matter and the forces at play within the atomic nucleus. This branch of physics has a wide range of applications, including nuclear energy production, medical imaging, and cancer treatments.

• Studies nuclear structure and behavior.
• Examines reactions, such as fission and fusion.
• Contributes to advancements in medical technologies.

Researchers in nuclear physics strive to understand the fundamental forces and particles that govern our universe. This includes investigating isotopes, decay processes, and how these influence our lives. By unlocking the secrets of the nucleus, this field continues to develop technologies that improve our daily lives and deepen our understanding of the universe.

Radioactivity

Radioactivity refers to the natural or induced process whereby unstable atomic nuclei lose energy by emitting radiation. This phenomenon is a key concept in nuclear physics and has practical applications in various fields, such as medicine, archaeology, and energy. There are several types of radioactive decay, including:

• Alpha decay: Emission of an alpha particle (helium nucleus).
• Beta decay: Transformation of a neutron into a proton through beta-ray emission.
• Gamma decay: Release of gamma radiation without changing the number of protons or neutrons.

These processes are crucial for understanding nuclear reactions and safety measures associated with handling radioactive materials. Despite its risks, radioactivity has enabled significant advancements in technology, including the ability to diagnose and treat medical conditions, explore archaeological artifacts, and power energy systems through nuclear reactors.