Problem 35 - A Complete Resource Book in Chemistry for JEE Main

Question

The vapour density of ozone is (a) 24 (b) 16 (c) 48 (d) 72

Step-by-Step Solution

Answer

The vapour density of ozone is 24.

Step 1: Understanding the Concept of Vapour Density

Vapour density is defined as the relative mass of a vapor compared to hydrogen at the same conditions and is given by the formula: \( \text{Vapour Density} = \frac{\text{Molecular Mass}}{2} \). In this question, we need to find the vapour density of ozone (\( O_3 \)).

Step 2: Determining the Molecular Mass of Ozone

First, let's find the molecular mass of ozone. Ozone is \( O_3 \), meaning it contains three oxygen atoms. The atomic mass of oxygen is 16 u. Therefore, the molecular mass of ozone is calculated as \( 3 \times 16 = 48 \) u.

Step 3: Calculate the Vapour Density

Use the formula for vapour density: \( \text{Vapour Density} = \frac{\text{Molecular Mass}}{2} \). Substituting the molecular mass of ozone, we get \( \text{Vapour Density} = \frac{48}{2} = 24 \).

Step 4: Choose the Correct Answer

From the options given, (a) 24 is the correct vapour density of ozone.

Key Concepts

Molecular Mass

The concept of molecular mass is essential in understanding various concepts in chemistry, and it plays a crucial role in solving problems related to gases, such as vapour density. Molecular mass is the sum of the atomic masses of all the atoms in a molecule. Each element has an atomic mass, which is the average mass of atoms of an element, usually expressed in atomic mass units (u). For example, the atomic mass of oxygen is 16 u, and if we consider a molecule like ozone, which is represented as \( O_3 \), we need to multiply the atomic mass of oxygen by three since there are three atoms in an ozone molecule:

• Molecular mass of \( O_3 \) = 3 x 16 u = 48 u

Understanding molecular mass is fundamental in calculating other properties of substances, including vapour density.

Ozone

Ozone is a fascinating molecule with the chemical formula \( O_3 \). It consists of three oxygen atoms linked together, forming a triatomic molecule. Ozone is known for its role in protecting life on Earth by absorbing harmful ultraviolet radiation in the stratosphere. This molecule not only plays a part in atmospheric chemistry, but it is also crucial in various industrial processes.

In terms of physical properties, understanding the molecular structure of ozone is key, especially when dealing with concepts like vapour density. As ozone consists of oxygen atoms, you can easily compute its molecular mass, as shown previously, making it an excellent practical example to connect molecular mass to real-world chemistry applications.

Chemistry Problem-Solving

Chemistry problem-solving often involves understanding and applying different concepts and formulae. To effectively solve chemistry problems, one needs a strong foundation in the basic principles. This includes knowing how to calculate the molecular mass and using this information to find other related properties, such as vapour density. In this case of finding the vapour density of ozone, the process is straightforward:

• Recognize the given chemical formula: \( O_3 \)
• Calculate molecular mass: 3 oxygen atoms x 16 u = 48 u
• Apply the vapour density formula: \( \text{Vapour Density} = \frac{\text{Molecular Mass}}{2} \)

This kind of step-by-step approach, using clearly defined concepts, ensures that students can tackle a variety of chemistry problems and find solutions confidently. Understanding how different concepts interrelate is crucial to mastering chemistry problem-solving.