Question

Ozone \(\left(\mathrm{O}_{3}\right)\) is a strong oxidizing agent that can oxidize all the common metals except gold and platinum. A convenient test for ozone is based on its action on mercury. When exposed to ozone, mercury becomes dull looking and sticks to glass tubing (instead of flowing freely through it). Write a balanced equation for the reaction. What property of mercury is altered by its interaction with ozone?

Short answer

The balanced equation is \(2\text{Hg} + \text{O}_3 \rightarrow 2\text{HgO} + \text{O}_2\). Mercury's surface becomes dull and sticky.

Step-by-step solution

Identify Reactants and Products

We begin by identifying what substances are involved in the reaction. The reactants in this scenario are mercury (Hg) and ozone (\(\text{O}_3\)). The oxidation reaction typically forms mercuric oxide (\(\text{HgO}\)) as the product when mercury reacts with ozone.

Write the Unbalanced Chemical Equation

Next, we write the chemical equation that represents the reaction between mercury and ozone: \[ \text{Hg} + \text{O}_3 \rightarrow \text{HgO} + \text{O}_2 \] Here, mercury (Hg) reacts with ozone (\(\text{O}_3\)) to form mercuric oxide (\(\text{HgO}\)) and oxygen (\(\text{O}_2\)).

Balance the Chemical Equation

The equation must have the same number of each type of atom on both sides. There is one mercury atom on both sides, but we need to adjust the oxygen atoms. We start by balancing the oxygen atoms: \[ 2\text{Hg} + \text{O}_3 \rightarrow 2\text{HgO} + \text{O}_2 \] Now, both sides have a total of 3 oxygen atoms, and 2 mercury atoms, making the equation balanced.

Analyze the Property Change

When mercury reacts with ozone, it forms an oxide layer on its surface. This reaction alters the surface property of mercury, causing it to lose its metallic luster and ability to flow freely as a liquid. The mercury becomes dull and adheres to glass surfaces due to the formation of mercuric oxide.

Key concepts

Ozone

Ozone, chemically represented as \( \text{O}_3 \), is a molecule composed of three oxygen atoms.
This allotrope of oxygen is known for being a strong oxidizing agent, capable of facilitating oxidation in various substances.
As an oxidizing agent, ozone can accept electrons from other elements or compounds, thereby oxidizing them.
Unlike the regular two-atom oxygen molecule, ozone has a distinct structure that makes it highly reactive and effective in various chemical reactions.

• Ozone occurs naturally in small amounts in the Earth's stratosphere, forming the ozone layer which protects the planet from harmful ultraviolet rays.
• It is also found at lower altitudes and may even be created through human activities, contributing to air pollution.

Its reactivity with substances like mercury exemplifies its potential to transfer oxygen atoms, altering the chemical structure of other materials.
Understanding ozone's properties is crucial to grasp its role in oxidation reactions.

Mercury

Mercury, denoted as \( \text{Hg} \), is a unique metallic element that remains liquid at room temperature.
Known for its silvery, lustrous appearance, mercury is often used in instruments like thermometers and barometers.
However, when mercury interacts with a strong oxidizing agent like ozone, its surface chemistry changes significantly.
In the described reaction, mercury loses its metallic sheen and becomes non-lustrous.

• Upon exposure to ozone, mercury's surface forms a layer of mercuric oxide \( \text{HgO} \), leading to loss of surface mobility and stickiness to glass surfaces.
• This transformation shows why ozone can alter the physical appearance and reduce the metallic properties of mercury.

Such reactions demonstrate how oxidation can fundamentally change a metal's properties, making mercury an interesting element to study when exploring chemical interactions.

Balanced Chemical Equation

A balanced chemical equation is fundamental in representing chemical reactions accurately, ensuring that the same number of each type of atom appears on both sides of the equation.
For the reaction between mercury and ozone, we start with:\[ \text{Hg} + \text{O}_3 \rightarrow \text{HgO} + \text{O}_2 \]To balance this equation, we align the number of mercury and oxygen atoms on both sides:
\[ 2\text{Hg} + \text{O}_3 \rightarrow 2\text{HgO} + \text{O}_2 \]

• Now, both sides have two mercury atoms and a total of three oxygen atoms, demonstrating a balanced chemical equation.
• This process ensures the principle of the conservation of mass is observed, critical in accurately describing chemical reactions.

Balancing chemical equations requires adjusting coefficients to reflect the same atom counts on both reaction sides, maintaining equilibrium.

Oxidizing Agent

An oxidizing agent is a substance that facilitates the oxidation of another by accepting electrons, often resulting in the alteration of the chemical composition of the substance it reacts with.
Ozone is an exemplary oxidizing agent because it can gain electrons from other substances, enabling it to impose oxidative changes.
In the reaction with mercury, ozone effectively oxidizes mercury, transforming it into mercuric oxide \( \text{HgO} \).

• Oxidizing agents are crucial in diverse reactions, ranging from industrial chemical processes to biological systems.
• Understanding the role and mechanism of oxidizing agents helps in predicting and controlling the outcomes of chemical reactions.

In the context of this exercise, the capability of ozone to serve as a strong oxidizing agent is clearly illustrated by its reaction with mercury, affecting both the chemical makeup and observable traits of the mercury.