Problem 64 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is formed when silver nitrate is treated with caustic soda? (a) \(\mathrm{Ag}_{3} \mathrm{~N}\) (b) \(\mathrm{Ag}\) (c) \(\mathrm{AgNO}_{2}\) (d) \(\mathrm{Ag}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

The product formed is \( \text{Ag}_2 \text{O} \), corresponding to option (d).

Step 1: Identify the Compounds Involved

Silver nitrate is represented as \( \text{AgNO}_3 \) and caustic soda is represented as \( \text{NaOH} \). We need to consider the reaction between these two compounds.

Step 2: Write the Chemical Equation

When silver nitrate (\( \text{AgNO}_3 \)) reacts with caustic soda (\( \text{NaOH} \)), it forms silver oxide (\( \text{Ag}_2 \text{O} \)), sodium nitrate (\( \text{NaNO}_3 \)), and water (\( \text{H}_2\text{O} \)). The balanced chemical equation is: \[2 \text{AgNO}_3 + 2 \text{NaOH} \rightarrow \text{Ag}_2 \text{O} + 2 \text{NaNO}_3 + \text{H}_2\text{O}\]

Step 3: Analyze the Reaction Products

Based on the chemical equation, the products are silver oxide \( \text{Ag}_2 \text{O} \), sodium nitrate \( \text{NaNO}_3 \), and water \( \text{H}_2\text{O} \). The substance corresponding to one of the multiple choices is \( \text{Ag}_2 \text{O} \).

Step 4: Select the Correct Answer

From the options provided, \( \text{Ag}_2 \text{O} \) matches option (d). Thus, \( \text{Ag}_2 \text{O} \) is formed when silver nitrate reacts with caustic soda.

Key Concepts

Silver Nitrate

Silver nitrate is a chemical compound with the formula \( \text{AgNO}_3 \). It is an inorganic compound frequently used in a laboratory setting for various reactions. One of its most notable characteristics is its solubility in water, making it a convenient reagent.

• **Appearance**: A colorless crystalline solid.
• **Solubility**: Highly soluble in water.
• **Uses**: Silver nitrate is often used in chemical synthesis and other applications like photography, disinfectants, and silver plating due to its ability to easily produce silver ions (\( \text{Ag}^+ \)).

Whenever silver nitrate is involved in a chemical reaction, it often produces a distinctive effect because of its silver content. In the reaction with caustic soda, it allows for the formation of silver oxide, a product useful in a variety of chemical applications.

Caustic Soda

Caustic soda, known chemically as sodium hydroxide (\(\text{NaOH}\)), is another highly useful chemical. It is a strong base and is commonly encountered in both industrial and household contexts.

• **Appearance**: A white, solid compound that is usually found in pellet or flake form.
• **Solubility**: Highly soluble in water, which results in a strongly basic solution.
• **Uses**: In addition to its industrial roles in the production of paper, detergents, and textiles, caustic soda is also used in household cleaning products and to unclog drains.

When caustic soda reacts with other chemicals, it typically results in the formation of a salt and sometimes the release of a gas, depending on the particular reaction. In the case of its reaction with silver nitrate, caustic soda facilitates the precipitation of silver oxide, which is an insoluble product.

Balanced Chemical Equation

A balanced chemical equation is crucial in understanding the stoichiometry of a chemical reaction. It ensures that the same number of each type of atom is present on both sides of the reaction equation.

For the reaction between silver nitrate and caustic soda where silver oxide, sodium nitrate, and water are formed, the balanced equation is:
\[2 \text{AgNO}_3 + 2 \text{NaOH} \rightarrow \text{Ag}_2 \text{O} + 2 \text{NaNO}_3 + \text{H}_2\text{O}\]

• **Reactants**: 2 moles of silver nitrate and 2 moles of sodium hydroxide.
• **Products**: 1 mole of silver oxide, 2 moles of sodium nitrate, and 1 mole of water.

Balancing chemical equations is critical because it follows the Law of Conservation of Mass—matter is neither created nor destroyed. This principle ensures that the chemical equation accurately reflects the quantitative relationships between reactants and products, providing insights into how much of each substance is needed or produced.