Problem 121 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following $$ \begin{array}{ll} \hline \text { Column-I } & \text { Column-II } \\ \hline \text { (a) } \mathrm{Ce}^{4+} & \text { (p) Oxidizing agent in volu- } \\\ \text { metric analysis } \\ \text { (b) } \mathrm{Nd}^{3+} & \text { (q) Misch metal } \\ \text { (c) } \mathrm{La}^{3+} & \text { (r) Colourless salts } \\ \text { (d) } \mathrm{Pr}^{3+} & \text { (s) Coloured glases for gog- } \\ \text { gles. } \end{array} $$

Step-by-Step Solution

Answer

a-p, b-q, c-r, d-s.

Step 1: Analyze Column-I

Column-I contains chemical ions: \( \mathrm{Ce}^{4+} \), \( \mathrm{Nd}^{3+} \), \( \mathrm{La}^{3+} \), and \( \mathrm{Pr}^{3+} \). We need to determine known uses or characteristics of each.

Step 2: Analyze Column-II

Column-II provides context for matching. It includes terms related to oxidizing agents, misch metal, color properties, and uses in colored glass for goggles.

Step 3: Matching \( \mathrm{Ce}^{4+} \) with Column-II

\( \mathrm{Ce}^{4+} \) is known to be an oxidizing agent, often used in volumetric analysis. Thus, it matches with (p) Oxidizing agent in volumetric analysis.

Step 4: Matching \( \mathrm{Nd}^{3+} \) with Column-II

\( \mathrm{Nd}^{3+} \) is typically used in alloys such as misch metal, which matches with (q) Misch metal.

Step 5: Matching \( \mathrm{La}^{3+} \) with Column-II

\( \mathrm{La}^{3+} \) generally forms colorless salts. It matches with (r) Colourless salts.

Step 6: Matching \( \mathrm{Pr}^{3+} \) with Column-II

\( \mathrm{Pr}^{3+} \) is used in the production of colored glasses, specifically in goggles. Thus, it matches with (s) Coloured glasses for goggles.

Key Concepts

Oxidizing Agents

Oxidizing agents are substances that have the ability to accept electrons from other substances in a chemical reaction. They are key players in oxidation-reduction (redox) reactions. The role of an oxidizing agent is to be reduced itself while oxidizing another substance. This means it gains electrons while the other substance loses them. An example of a strong oxidizing agent is cerium(IV) ion, \( \mathrm{Ce}^{4+} \). It's often used in volumetric analysis because of its ability to act as an electron acceptor. Cerium(IV) salts in solution can readily gain electrons, making them highly effective in providing a clear endpoint in titrations.The oxidizing power of \( \mathrm{Ce}^{4+} \) is frequently utilized in analytical chemistry to determine the concentration of reducing agents in a sample. This makes oxidizing agents indispensable tools in both industrial processes and laboratory experiments.

Misch Metal

Misch metal is an alloy primarily composed of rare-earth elements such as cerium and neodymium. It is commonly used in manufacturing industries due to its unique properties. One of the principal uses of misch metal is in the production of flints for lighters. It sparks when struck against a rough surface, igniting the lighter fluid. Neodymium, \( \mathrm{Nd}^{3+} \), in misch metal offers beneficial properties such as corrosion resistance and heat-resistance.Besides generating sparks, misch metal is valuable in producing specialty steels and non-ferrous metals, enhancing strength and durability. Its rarity and specific characteristics make it a desirable component in advanced technologies and high-performance alloys.

Color Properties

The color properties of ions can be fascinating, given their profound impact on everyday objects like glasses and ceramics. When ions absorb certain wavelengths of light, it imparts color to the materials they are in. Praseodymium, \( \mathrm{Pr}^{3+} \), is one of the ions renowned for its color properties. It's often used in colored glasses for goggles because of its ability to absorb yellow and red wavelengths, giving goggles a distinctive appearance. These colored glasses are crucial in protecting eyes in high-visibility contexts such as welding and glass-blowing.On the other hand, lanthanum, \( \mathrm{La}^{3+} \), typically forms colorless salts. This characteristic is particularly useful in applications where a neutral, non-distracting appearance is essential, such as in optical lenses and precision instruments.

Volumetric Analysis

Volumetric analysis is a technique in chemistry used to determine the concentration of a solute in a solution by titration. In this process, a solution of known concentration, called the titrant, is added to a solution of the analyte until the reaction reaches its endpoint. The use of oxidizing agents, like \( \mathrm{Ce}^{4+} \), plays a crucial role in volumetric analysis. They enable precise quantification of reducing agents by reacting in a predictable manner, allowing the exact concentration to be calculated via stoichiometry. Volumetric analysis is widely used in various industries, including pharmaceuticals and environmental science. It provides accurate measurements that are crucial, for example, in determining the purity of a substance or assessing the levels of pollutants in a sample. The accuracy and efficiency of volumetric analysis make it an essential tool in both educational settings and practical chemical analysis applications.