Question

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

Short answer

The vapour density of ozone is 24, so the answer is (a).

Step-by-step solution

Understanding Vapour Density

The vapour density of a gaseous substance is defined as half the molar mass. Mathematically, it is expressed as: \[ \text{Vapour Density} = \frac{\text{Molar Mass}}{2} \].

Determine Molar Mass of Ozone

Ozone, symbolized as \( O_3 \), consists of three oxygen atoms. The atomic mass of oxygen is approximately 16 g/mol. Therefore, the molar mass of ozone will be: \[ 3 \times 16 = 48 \text{ g/mol} \].

Calculate Vapour Density of Ozone

Using the formula for vapour density, substitute the molar mass of ozone: \[ \text{Vapour Density} = \frac{48}{2} = 24 \].

Select the Correct Answer

The calculated vapour density of ozone is 24, which corresponds to option (a).

Key concepts

Molar Mass

To understand the concept of molar mass, think about it as the weight of a single molecular entity, typically given in grams per mole (g/mol). For any chemical compound, the molar mass is calculated by summing up the atomic masses of all atoms present in its molecular formula.
In the context of ozone (\( O_3 \)), its molar mass calculation involves the atomic masses of three oxygen atoms. The atomic mass of an oxygen atom is approximately 16 g/mol, resulting in a molar mass of:

• 3 atoms of Oxygen: \( 3 \times 16 = 48 \text{ g/mol} \)

Molar mass is crucial for various chemical calculations, such as determining the vapor density or converting moles to grams and vice versa. Understanding molar mass helps in accurately measuring the amount of substance needed for reactions and processes.

Ozone Chemistry

Ozone is a simple but significant molecule symbolized as \( O_3 \). It consists of three oxygen atoms bonded together. Found most commonly in the Earth's stratosphere, it forms the protective ozone layer that absorbs and blocks the majority of the sun's ultraviolet radiation.
Ozone is known for its

• ability to absorb harmful UV rays, thereby protecting life on Earth
• distinct smell often associated with clean air after a thunderstorm
• role as a pollutant at ground level, where it can contribute to respiratory problems

Its chemistry is noteworthy because it serves distinct roles in different contexts, oscillating between a protective shield in the stratosphere and a pollutant in the lower atmosphere. These dual roles highlight the importance of understanding the chemical properties and dynamics of ozone in both environmental science and public health discussions.

Atomic Mass of Oxygen

The atomic mass of an element is a weighted average of all the isotopes of that element, reflecting both mass and abundance. For oxygen, the atomic mass is approximately 16 g/mol.
This means that a mole of oxygen atoms has a mass of about 16 grams. This measure is vital in calculations involving chemical reactions, where precise measurement of input substances is required for accuracy and efficiency.

• Atomic mass allows chemists to predict the amount of reactants and products involved in chemical processes with precision.
• It provides a foundation upon which calculations like molar mass and vapor density are based.

Considering the atomic mass of oxygen is fundamental to working with compounds like ozone, as it allows for accurate determination of ozone's molar mass, which in turn is necessary for calculating other properties like vapor density.