Problem 120 - A Complete Resource Book in Chemistry for JEE Main

Question

Select the correct statements: (a) In the reaction \({ }_{11} \mathrm{Na}^{23}+\mathrm{Q} \rightarrow{ }_{12} \mathrm{Mg}^{23}+{ }_{0} \mathrm{n}^{1}\), the bombarding particle \(\mathrm{q}\) is deutron (b) In the reaction \({ }_{92} \mathrm{U}^{235}+{ }_{0} \mathrm{n}^{1} \rightarrow 56 \mathrm{Ba}^{140}+2\) \({ }_{0} \mathrm{n}^{\prime}+\mathrm{p}\), produced \(\mathrm{p}\) is \({ }_{36} \mathrm{Kr}^{94}\) (c) In a fission reaction, a loss in mass occurs releasing a huge amount of energy (d) A huge amount of energy is produced during nuclear fission and nuclear fussion reaction

Step-by-Step Solution

Answer

Statements (c) and (d) are correct.

Step 1: Analyze Statement (a)

The reaction given is \( { }_{11} \mathrm{Na}^{23} + \mathrm{Q} \rightarrow { }_{12} \mathrm{Mg}^{23} + { }_{0} \mathrm{n}^{1} \). To identify the bombarding particle \( \mathrm{Q} \), we consider the change in atomic number from Na (11) to Mg (12). This indicates that a proton (\( { }_{1} \mathrm{H}^{2} \), deuteron) has been added, maintaining the nucleon number. Hence, the statement is incorrect because the correct bombarding particle Q should be a proton.

Step 2: Evaluate Statement (b)

The type of reaction described suggests a nuclear fission event involving \( { }_{92} \mathrm{U}^{235} \) leading to \( { }_{56} \mathrm{Ba}^{140} \). The problem presents \( 2{ }_{0} \mathrm{n}^{1} + \mathrm{p} \) in the products which are typically neutrons. Hence, the statement's reference \( 36 \mathrm{Kr}^{94} \) indicates a mistake as \( \mathrm{Kr}^{94} \) should be one of the fission fragments, not a proton. Therefore, this statement is incorrect.

Step 3: Consider Statement (c)

During nuclear fission reactions, a small loss in mass indeed occurs due to the conversion of mass into energy as described by \( E=mc^2 \). This mass defect is responsible for the release of a large amount of energy. Thus, this statement is correct.

Step 4: Verify Statement (d)

Both nuclear fission and fusion reactions release large amounts of energy. Fission splits heavy nuclei, while fusion combines light nuclei. Each process inherently produces substantial energy due to the conversion of mass to energy. Therefore, this statement is correct.

Key Concepts

Understanding Nuclear Fission

Nuclear fission is a process where a heavy nucleus splits into two or more smaller nuclei, along with the release of a significant amount of energy. This usually occurs when a heavy nucleus, like uranium-235, absorbs a neutron. The nucleus becomes unstable and divides into smaller nuclei, such as barium-140 and krypton-94 in a typical fission reaction.

• The fission process also releases additional neutrons, which can initiate further fission reactions, creating a chain reaction.
• This chain reaction is harnessed in nuclear reactors to produce energy.
• Fission is characterized by a mass defect, where the mass of the products is slightly less than the original nucleus. This mass difference is converted into energy.

This energy conversion is explained by Einstein’s famous equation, which we'll discuss later.

Exploring Nuclear Fusion

Nuclear fusion is the process of combining two light nuclei to form a heavier nucleus, which releases energy. Fusion is the reaction that powers stars, including our sun, where hydrogen nuclei fuse to form helium.

• In fusion, lighter elements like hydrogen isotopes - deuterium and tritium - are merged under high temperature and pressure conditions.
• Fusion reactions release more energy per unit mass than fission reactions.
• However, achieving the conditions necessary for fusion on Earth is challenging and is currently a hot topic in scientific research.

The prospect of harnessing fusion for energy is appealing due to its potential for providing a nearly limitless and cleaner energy source than current nuclear fission reactors.

Mass-Energy Equivalence Explained

The concept of mass-energy equivalence is beautifully explained by Einstein’s equation: \[ E = mc^2 \].This formula shows how mass can be converted into energy. In nuclear reactions, the small amount of mass loss translates into a large amount of energy due to the speed of light (\( c \), approximately \( 3 \times 10^8 \) m/s) being a very large number.

• During both fission and fusion, the mass of the products is less than the mass of the reactants.
• This 'missing' mass has been converted into energy, accounting for the substantial energy release observed in nuclear reactions.
• Understanding this principle is crucial in both scientific research and practical applications like nuclear power generation.

Mass-energy equivalence links the two powerful processes of fission and fusion to their energy outputs, showing their potential and critical role in advancing energy technology.