Problem 1 - Chemistry in 30 days

Question

What gas is produced when red lead is treated with conc. nitric acid ? (a) NO (b) \(\mathrm{NO}_{2}\) (c) both Type_ro (d) none

Step-by-Step Solution

Answer

The gas produced is (b) \( \mathrm{NO}_{2} \).

Step 1: Identify the Reaction

The chemical reaction involved consists of red lead ( ext{Pb}_3 ext{O}_4) reacting with concentrated nitric acid ( ext{HNO}_3). This reaction is important for determining which gases are produced.

Step 2: Consider Reaction Components

In the reaction between red lead and nitric acid, the nitric acid may either oxidize or reduce. It can produce nitrogen oxides as byproducts, primarily nitrogen dioxide ( ext{NO}_2) since red lead serves as an oxidizer.

Step 3: Write Balanced Chemical Equation

At this step, we write the balanced chemical equation for the reaction: \[ ext{Pb}_3 ext{O}_4 + 8 ext{HNO}_3 ightarrow 3 ext{Pb}( ext{NO}_3)_2 + 4 ext{H}_2 ext{O} + 2 ext{NO}_2\]This equation shows the gases produced include ext{NO}_2.

Step 4: Identify Gases Produced

From the equation, it is clear that nitrogen dioxide ( ext{NO}_2) is produced, indicated by the appearance of the term ext{NO}_2 on the product side of the chemical reaction.

Key Concepts

Understanding Chemical Reactions

The foundation of inorganic chemistry lies in understanding how chemical reactions occur. At its core, a chemical reaction involves the transformation of one or more substances, termed reactants, into different substances, known as products. This transformation involves breaking and forming chemical bonds. For our particular reaction, red lead (Pb\(_3\)O\(_4\)) reacts with concentrated nitric acid (HNO\(_3\)), highlighting a combination of solid and liquid reactants that interact to form various products.

• Reactants are the starting materials in a chemical reaction.
• Products are the materials formed as a result of the reaction.

Balancing chemical equations is crucial. It ensures that the number of atoms for each element is the same on both sides of the equation, maintaining the principle of the conservation of mass. In our exercise, the balanced equation is:\[\text{Pb}_3\text{O}_4 + 8\text{HNO}_3 \rightarrow 3\text{Pb}(\text{NO}_3)_2 + 4\text{H}_2\text{O} + 2\text{NO}_2\]This equation determines the stoichiometric ratios used to predict the amount of each product formed.

Exploring Nitrogen Oxides

Nitrogen oxides are a group of gaseous compounds composed of nitrogen and oxygen. In this reaction, the focus is primarily on nitrogen dioxide (NO\(_2\)) and nitric oxide (NO).

• Nitric oxide is a colorless gas that, under typical conditions, readily oxidizes to form nitrogen dioxide.
• Nitrogen dioxide is a reddish-brown gas with a sharp, biting odor, and is a significant air pollutant.

These oxides are commonly formed during the reaction of nitric acid with various oxidizers, such as lead(IV) oxide found in red lead. In environmental and industrial contexts, nitrogen oxides contribute to air pollution and can be harmful. In this exercise, the chemical equation confirms the production of NO\(_2\) as a gas.

Role of Red Lead in Reactions

Red lead, or triplumbic tetraoxide (Pb\(_3\)O\(_4\)), is an important inorganic compound. It acts as an oxidizing agent in chemical reactions. In the context of our exercise, red lead reacts with nitric acid. Its primary role is to provide oxygen for oxidation processes.

• Red lead is often used in batteries, rust proofing, and pigments due to its stability and color.
• In reactions, it can serve as an oxidizer, facilitating the transformation of nitric acid into nitrogen oxides.

The interaction between red lead and nitric acid exemplifies the behavior of red lead as a catalyst in redox reactions, giving rise to products like nitrogen dioxide.

Properties and Uses of Nitric Acid

Nitric acid, HNO\(_3\), is a powerful mineral acid commonly used in laboratories and industry. It has several key properties and uses:

• It is a strong oxidizing agent, capable of adding oxygen or removing hydrogen in chemical reactions.
• It is colorless, but upon standing forms a yellowish pall due to the decomposition that releases nitrogen dioxide (NO\(_2\)).

Nitric acid plays a crucial role in our chemical reaction with red lead, facilitating the production of nitrogen oxides. Industrially, it is involved in the manufacturing of fertilizers, explosives, and in metal refining processes. Its ability to react with metals, oxides, and a variety of organic compounds makes it indispensable in several chemical syntheses.