Question

A main source of sulfur oxide pollutants are smelters where sulfide ores are converted into metals. The first step in this process is the reaction of the sulfide ore with oxygen in reactions such as: (a) \(2 \mathrm{PbS}(s)+3 \mathrm{O}_{2}(g) \underset{\mathrm{UV} \text { light }}{\longrightarrow} 2 \mathrm{PbO}(s)+2 \mathrm{SO}_{2}(g)\) Sulfur dioxide can then react with oxygen in air to form sulfur trioxide: (b) \(2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{SO}_{3}(g)\) Sulfur trioxide can then react with water from rain to form sulfuric acid that falls as acid rain: (c) \(\mathrm{SO}_{3}(g)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}_{2} \mathrm{SO}_{4}(a q)\) Classify each of the preceding reactions \((a, b, c)\) as a synthesis, decomposition, single-displacement, or doubledisplacement reaction.

Short answer

Reaction (a) is a synthesis reaction, reaction (b) is a synthesis reaction, and reaction (c) is a synthesis reaction.

Step-by-step solution

Classify Reaction (a)

Examine the reactants and products in reaction (a) to determine the type of reaction. The reaction has one type of compound (PbS) reacting with a pure element (O2) to form different compounds (PbO and SO2). This is a synthesis reaction where simple substances combine to form a more complex substance.

Classify Reaction (b)

Review the reactants and products in reaction (b). We see that two molecules of sulfur dioxide (SO2) are reacting with a molecule of oxygen (O2) to form sulfur trioxide (SO3). This reaction is another example of a synthesis reaction, as two or more substances combine to form a new compound.

Classify Reaction (c)

Analyze the reactants and products in reaction (c). Sulfur trioxide (SO3) reacts with water (H2O) to produce sulfuric acid (H2SO4). This is also a synthesis reaction, since a compound is formed from the combination of two molecules.

Key concepts

Understanding Synthesis Reactions

Synthesis reactions are fundamental to the study of chemistry—they're like the building blocks of more complex substances. Simply put, during a synthesis reaction, two or more substances combine to form a new compound. This might remind you of making a recipe where you mix ingredients to create a dish; similarly, in chemistry, when elements like oxygen mix with other substances, they can create entirely new compounds with distinct properties.

For instance, in the textbook example (a), lead sulfide (PbS) and oxygen (O₂) combine to form lead(II) oxide (PbO) and sulfur dioxide (SO₂). It's like a dance where partners (the reactants) join hands (combine) to form a dance group (the product). This joining of hands represents the formation of new chemical bonds during the reaction.

Sulfur Oxide Pollutants and Their Impact

When we talk about sulfur oxide pollutants, mainly sulfur dioxide (SO₂) and sulfur trioxide (SO₃), we're delving into the not-so-pleasant side of chemical reactions. These pollutants are typically byproducts of industrial processes, such as the smelting of sulfide ores, as mentioned in our textbook exercise.

Sulfur oxides are particularly notorious for their role in creating acid rain. When released into the atmosphere, they can react further—to build upon the metaphor, it's like a dance group that decides to bring in rain clouds to their performance, which might make the show a bit unpleasant for the audience. In the same way, when sulfur oxides dance with water in the atmosphere, they form sulfuric acid, leading to environmental issues like acid rain. This reaction showcases the real-world impact of chemical processes, emphasizing the importance of understanding and potentially controlling these reactions.

The Formation of Acid Rain

Acid rain is not just a problem for statues and buildings; it's an environmental issue that affects water bodies, forests, and even our health. The formation of acid rain is a sort of tragic play in the theater of chemistry, where compounds produced from human activity transform in the atmosphere and fall back to Earth in a more harmful form.

Following exercise example (c), sulfur trioxide joins with water to create sulfuric acid. Picture it as a nefarious transformation—from a benign vapor waltzing in the air (SO₃) to a substance (H₂SO₄) that can corrode and damage everything it touches. It's this final reaction of synthesis that reveals the acidity in the rain, exposing the dangers inherent in seemingly simple chemical reactions. By understanding such processes, we can better appreciate the complexities and consequences of our industrial actions, and hopefully, find ways to mitigate such adverse effects.