Problem 133 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following Column-I (a) \(\mathrm{Sn}+\) conc. \(\mathrm{HNO}_{3}\) (b) \(\mathrm{Sn}+\mathrm{di} . \mathrm{HNO}_{3}\) (c) \(\mathrm{Ag}+\) conc. \(\mathrm{HNO}_{3}\) (d) \(\mathrm{Ag}+\) dil. \(\mathrm{HNO}_{3}\) Column-II (p) NO (q) \(\mathrm{NO}_{2}\) (r) \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) (s) \(\mathrm{Sn}\left(\mathrm{NO}_{3}\right)_{2}\) (t) \(\mathrm{AgNO}_{3}\)

Step-by-Step Solution

Answer

(a) Sn + conc. HNO₃ = NO₂, Sn(NO₃)₂; (b) Sn + dil. HNO₃ = NH₄NO₃, Sn(NO₃)₂; (c) Ag + conc. HNO₃ = NO₂, AgNO₃; (d) Ag + dil. HNO₃ = NO, AgNO₃.

Step 1: Understand Reaction Scenarios

We need to match chemical reactions from Column-I with their resulting products or byproducts in Column-II. In each scenario, tin (Sn) or silver (Ag) reacts with nitric acid (HNO₃), which can be in concentrated or dilute form. Concentrated HNO₃ typically produces more oxidizing environments than dilute HNO₃.

Step 2: Analyze Reaction of Sn with Conc. HNO₃

When tin (Sn) reacts with concentrated nitric acid, a redox reaction occurs. Normally, in such scenarios, nitrogen dioxide (NO₂), characterized by brown fumes, is released as a byproduct, and tin nitrate, Sn(NO₃)₂, is formed as a product. Thus, the reaction is (a) Sn + conc. HNO₃ → NO₂ and Sn(NO₃)₂.

Step 3: Analyze Reaction of Sn with Dil. HNO₃

When tin (Sn) reacts with dilute nitric acid, tin nitrate (Sn(NO₃)₂) is formed, and one of the principal byproducts is typically ammonium nitrate (NH₄NO₃), formed by the reduction of nitric acid. This can lead to less oxidizing byproducts. Thus, the reaction is (b) Sn + dil. HNO₃ → NH₄NO₃ and Sn(NO₃)₂.

Step 4: Analyze Reaction of Ag with Conc. HNO₃

Silver (Ag), when reacted with concentrated nitric acid, generally forms silver nitrate (AgNO₃) as the main product, with nitrogen dioxide (NO₂) being released as the primary byproduct. Thus, the reaction is (c) Ag + conc. HNO₃ → NO₂ and AgNO₃.

Step 5: Analyze Reaction of Ag with Dil. HNO₃

When silver (Ag) reacts with dilute nitric acid, silver nitrate (AgNO₃) forms, and nitric oxide (NO) is usually produced as a byproduct. This happens due to the moderate oxidation strength of dilute nitric acid. Thus, the reaction is (d) Ag + dil. HNO₃ → NO and AgNO₃.

Key Concepts

Tin Reactions

Tin (Sn) is a versatile metal that can engage in redox reactions, particularly when exposed to nitric acid (HNO₃). When tin is subjected to concentrated nitric acid, it undergoes a redox reaction resulting in the formation of tin nitrate \( \text{Sn(NO}_3\text{)}_2 \) and the release of nitrogen dioxide \( \text{NO}_2 \), which is noticeable due to its characteristic brown fumes.
On the other hand, when tin reacts with dilute nitric acid, it still forms tin nitrate \( \text{Sn(NO}_3\text{)}_2 \), but the reaction favors the formation of ammonium nitrate \( \text{NH}_4\text{NO}_3 \) as one of the primary byproducts. This difference in reaction patterns is a result of the varying oxidation capabilities of concentrated versus dilute nitric acid. The possible formation of these different nitrates highlights tin's adaptable chemical behavior in acidic environments.

Silver Reactions

Silver (Ag) also reacts with nitric acid, a common occurrence in redox reactions entailing the formation of different nitrates. When silver interacts with concentrated nitric acid, it forms silver nitrate \( \text{AgNO}_3 \) and produces nitrogen dioxide \( \text{NO}_2 \) as a byproduct, recognizable by its brown fumes.
In contrast, when dilute nitric acid is used, the reaction primarily results in silver nitrate \( \text{AgNO}_3 \) and nitric oxide \( \text{NO} \) as a gaseous byproduct. This shift in byproduct formation arises due to the less aggressive oxidizing nature of dilute nitric acid, compared to its concentrated counterpart. Both reactions showcase the utility of silver in generating important compounds while releasing different nitrogen oxides based on the acid concentration.

Nitric Acid Concentration Effects

Nitric acid is a multifaceted reagent, known for its strong oxidizing characteristics when concentrated, and moderately oxidizing nature when diluted. The concentration of nitric acid plays a critical role in determining the outcome of its reactions with metals like tin and silver.

• Concentrated nitric acid tends to produce \( \text{NO}_2 \), releasing it as brown fumes, indicative of its robust oxidative properties.
• In contrast, dilute nitric acid generally leads to the generation of \( \text{NH}_4\text{NO}_3 \) or \( \text{NO} \) depending on the metal reacting with it, due to its comparatively gentler oxidation conditions.

The variance between concentrated and dilute forms highlights their different capacities to modify metal oxidations, leading to distinct byproducts and products. This knowledge is crucial in predicting reaction outcomes in both academic and practical chemical applications.

Reaction Products Identification

Identifying reaction products in the redox reactions of tin and silver with nitric acid involves understanding both the reactants and the conditions under which they react. Clarity in this recognition aids in accurately predicting the chemical outcomes.

• For tin with concentrated nitric acid, the products are \( \text{Sn(NO}_3\text{)}_2 \) and \( \text{NO}_2 \).
• With dilute nitric acid, \( \text{Sn(NO}_3\text{)}_2 \) and \( \text{NH}_4\text{NO}_3 \) emerge as reaction products.
• Silver, when reacted with concentrated nitric acid, produces \( \text{AgNO}_3 \) and \( \text{NO}_2 \).
• With dilute nitric acid, \( \text{AgNO}_3 \) and \( \text{NO} \) are formed.

Understanding these products not only helps in performing the reactions safely and efficiently in a lab but also aids in applying this knowledge in industries where such reactions may be used for silver refining or nitrate production.