Problem 27 - Chemistry: An Atoms-Focused Approach

Question

Chemistry of Volcanic Gases Balance the following reactions that occur during volcanic eruptions: a. \(\mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{3}(g)\) b. \(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)\) c. \(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+\mathrm{H}_{2} \mathrm{O}(g)\)

Step-by-Step Solution

Answer

Question: Balance the following chemical equations that occur during volcanic eruptions: a. Reaction: \(\mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{3}(g)\) b. Reaction: \(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)\) c. Reaction: \(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+\mathrm{H}_{2} \mathrm{O}(g)\) Answer: a. Balanced equation: \(\mathrm{SO}_{2}(g)+\frac{1}{2}\mathrm{O}_{2}(g) \rightarrow 2\mathrm{SO}_{3}(g)\) b. Balanced equation: \(\mathrm{H}_{2} \mathrm{S}(g)+\frac{1}{2}\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)\) c. Balanced equation: \(8\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+4\mathrm{H}_{2} \mathrm{O}(g)\)

Step 1: Identify atoms to balance

Begin by identifying the atoms present in the equation, which are Sulfur (S) and Oxygen (O).

Step 2: Balance Sulfur atoms

The number of sulfur atoms is equal on both sides (1 on the left and 1 on the right), so no changes are needed for sulfur.

Step 3: Balance Oxygen atoms

There are 4 oxygen atoms on the left side of the equation (2 in \(\mathrm{SO}_{2}\), and 2 in \(\mathrm{O}_{2}\)) and only 3 on the right side. To balance this out, multiply \(\mathrm{SO}_{3}\) by 2 on the right side. The balanced equation is: \(\mathrm{SO}_{2}(g)+\frac{1}{2}\mathrm{O}_{2}(g) \rightarrow 2\mathrm{SO}_{3}(g)\). b. Reaction: \(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)\)

Step 1: Identify atoms to balance

In this reaction, the atoms present are Hydrogen (H), Sulfur (S), and Oxygen (O).

Step 2: Balance Hydrogen atoms

There are 2 hydrogen atoms on the left side and 2 on the right side, so no changes are needed for hydrogen.

Step 3: Balance Sulfur atoms

Similarly, there is 1 sulfur atom on the left side and 1 on the right side. No changes are necessary for sulfur.

Step 4: Balance Oxygen atoms

There are 2 oxygen atoms on the left side and 3 on the right side. To balance this, simply multiply \(\mathrm{O}_{2}\) on the left side by \(\frac{1}{2}\). The balanced equation is: \(\mathrm{H}_{2} \mathrm{S}(g)+\frac{1}{2}\mathrm{O}_{2}(g) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)\). c. Reaction: \(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+\mathrm{H}_{2} \mathrm{O}(g)\)

Step 1: Identify atoms to balance

In this reaction, the atoms present are Hydrogen (H), Sulfur (S), and Oxygen (O).

Step 2: Balance Sulfur atoms

There are 2 sulfur atoms on the left side (1 in \(\mathrm{H}_{2} \mathrm{S}\) and 1 in \(\mathrm{SO}_{2}\)), but there are 8 sulfur atoms in \(\mathrm{S}_{8}\) on the right side. To balance this, multiply \(\mathrm{H}_{2} \mathrm{S}\) on the left side by 8, which gives the balanced sulfur atoms: \(8\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+\mathrm{H}_{2} \mathrm{O}(g)\).

Step 3: Balance Hydrogen atoms

With 8 hydrogen atoms on the left side now (8 in \(8\mathrm{H}_{2} \mathrm{S}\)), we need to multiply \(\mathrm{H}_{2} \mathrm{O}\) on the right side by 4 to balance the hydrogen atoms: \(8\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+4\mathrm{H}_{2} \mathrm{O}(g)\).

Step 4: Balance Oxygen atoms

Now, there are 4 oxygen atoms on the left and right sides (2 in \(\mathrm{SO}_{2}\) and 2 in \(4\mathrm{H}_{2} \mathrm{O}\)), so the equation is balanced: \(8\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{SO}_{2}(g) \rightarrow \mathrm{S}_{8}(s)+4\mathrm{H}_{2} \mathrm{O}(g)\).

Key Concepts

Volcanic Gases Chemistry

Volcanic eruptions release a variety of gases into the atmosphere, which can have significant environmental and health impacts. The primary gases released include water vapor, carbon dioxide, and sulfur compounds such as sulfur dioxide (\(\text{SO}_2\)). These gases result from the intense heat and pressure beneath the earth's crust, causing chemical reactions that release gases trapped in magma. Understanding the chemistry of volcanic gases is crucial as these gases can influence weather patterns, climate change, and air quality. When volcanic gases interact with atmospheric components, they may form aerosols, which can lead to phenomena like acid rain. By studying volcanic gas emissions, scientists can also gain insights into the dynamics of volcanic eruptions and potentially predict future eruptions.

Sulfur Dioxide Reactions

Sulfur dioxide (\(\text{SO}_2\)) is a significant pollutant that emerges from both natural and anthropogenic sources, with volcanic eruptions being one of the major natural sources. Sulfur dioxide is a colorless gas with a sharp, irritating odor and plays a critical role in atmospheric chemistry. It can react with water to form sulfurous acid, contributing to acid rain when dissolved in atmospheric moisture.
Sulfur dioxide also participates in reactions that lead to the formation of sulfate aerosols. These aerosols can reflect sunlight and cause cooling in the atmosphere. The reactions involved are crucial in forming association products like \(\text{SO}_3\) (sulfur trioxide), which further reacts with water to yield sulfuric acid.

• Sulfur dioxide can react with oxygen to form sulfur trioxide: \(\text{SO}_2 + \frac{1}{2}\text{O}_2 \rightarrow \text{SO}_3\).
• Another reaction it undergoes involves hydrogen sulfide to form elemental sulfur: \(\text{H}_2\text{S} + \text{SO}_2 \rightarrow \text{S}_8 + \text{H}_2\text{O}\).

These reactions are fundamental for understanding how sulfur dioxide impacts environmental chemistry.

Stoichiometry

Stoichiometry is a branch of chemistry that studies the quantitative relationships, or ratios, of reactants and products in a chemical reaction. It's the "recipe" of chemistry, letting us predict how much of each substance is needed or produced in a reaction.
By using balanced chemical equations, stoichiometry allows scientists to calculate everything from the amount of energy produced in a reaction to the amount of product formed. When dealing with volcanic gases, understanding stoichiometry helps predict the environmental impact of volcanic eruptions.

• Consider the reaction \(\text{SO}_2 + \frac{1}{2}\text{O}_2 \rightarrow \text{SO}_3\). Balancing it ensures that all sulfur and oxygen atoms on the reactant side equal those on the product side.
• Stoichiometry requires a careful count of atoms and how they are transformed throughout the reaction. For example, 1 molecule of \(\text{SO}_2\) reacts with \(\frac{1}{2}\) a molecule of \(\text{O}_2\) to produce 1 molecule of \(\text{SO}_3\).

Mastery of stoichiometry is essential for chemists when predicting the outcomes of even complex geochemical emissions, like those arising from volcanic activities.