Sulfuric acid | Structure, Formula, Uses, & Facts (2024)

Related Topics:: oxyacid; sulfur dioxide; acid; sulfation; vitriol

sulfuric acid, dense, colourless, oily, corrosive liquid; one of the most commercially important of all chemicals. Sulfuric acid is prepared industrially by the reaction of water with sulfur trioxide (see sulfur oxide), which in turn is made by chemical combination of sulfur dioxide and oxygen either by the contact process or the chamber process. In various concentrations the acid is used in the manufacture of fertilizers, pigments, dyes, drugs, explosives, detergents, and inorganic salts and acids, as well as in petroleum refining and metallurgical processes. In one of its most familiar applications, sulfuric acid serves as the electrolyte in lead–acid storage batteries.

Pure sulfuric acid has a specific gravity of 1.830 at 25 °C (77 °F); it freezes at 10.37 °C (50.7 °F). When heated, the pure acid partially decomposes into water and sulfur trioxide; the latter escapes as a vapour until the concentration of the acid falls to 98.3 percent. This mixture of sulfuric acid and water boils at a constant temperature of 338 °C (640 °F) at one atmosphere pressure. Sulfuric acid is commonly supplied at concentrations of 78, 93, or 98 percent.

Sulfuric acid | Structure, Formula, Uses, & Facts (2)

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oxyacid: Sulfuric acid

Due to its affinity for water, pure anhydrous sulfuric acid does not exist in nature. Volcanic activity can result in the production of sulfuric acid, depending on the emissions associated with specific volcanoes, and sulfuric acid aerosols from an eruption can persist in the stratosphere for many years. These aerosols can then reform into sulfur dioxide (SO₂), a constituent of acid rain, though volcanic activity is a relatively minor contributor to acid rainfall.

Sulfuric acid is a very strong acid; in aqueous solutions it ionizes completely to form hydronium ions (H₃O⁺) and hydrogen sulfate ions (HSO₄⁻). In dilute solutions the hydrogen sulfate ions also dissociate, forming more hydronium ions and sulfate ions (SO₄²⁻). In addition to being an oxidizing agent, reacting readily at high temperatures with many metals, carbon, sulfur, and other substances, concentrated sulfuric acid is also a strong dehydrating agent, combining violently with water; in this capacity, it chars many organic materials, such as wood, paper, or sugar, leaving a carbonaceous residue.

The term fuming sulfuric acid, or oleum, is applied to solutions of sulfur trioxide in 100 percent sulfuric acid; these solutions, commonly containing 20, 40, or 65 percent sulfur trioxide, are used for the preparation of organic chemicals.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Melissa Petruzzello.

The sulfur cycle is a fundamental process governing the movement and transformation of sulfur throughout Earth's ecosystems. As an enthusiast in environmental sciences, particularly biogeochemical cycles, I've delved deep into understanding the intricacies of the sulfur cycle.

Let's break down the concepts mentioned in the article:

Sulfuric Acid (H2SO4): Described as a dense, colorless, corrosive liquid, sulfuric acid is a pivotal chemical in various industries. Its industrial preparation involves the reaction of water with sulfur trioxide, synthesized from sulfur dioxide and oxygen via the contact or chamber process. It finds extensive use in fertilizers, pigments, dyes, drugs, explosives, detergents, petroleum refining, metallurgical processes, and as an electrolyte in lead-acid batteries.
Properties of Sulfuric Acid: Pure sulfuric acid possesses a specific gravity of 1.830 at 25 °C and freezes at 10.37 °C. When heated, it decomposes into water and sulfur trioxide, vaporizing until its concentration falls to 98.3 percent. This mixture boils at a constant temperature of 338 °C at one atmosphere pressure. Commercially, sulfuric acid is supplied at concentrations of 78, 93, or 98 percent.
Natural Occurrence: Anhydrous sulfuric acid doesn't exist naturally due to its strong affinity for water. However, volcanic activity can lead to sulfuric acid production, contributing to acid rain through emissions like sulfur dioxide (SO2). Sulfuric acid aerosols resulting from volcanic eruptions can persist in the stratosphere for extended periods.
Chemical Properties: Sulfuric acid, a potent acid, ionizes completely in aqueous solutions to form hydronium ions (H3O+) and hydrogen sulfate ions (HSO4−). In dilute solutions, hydrogen sulfate ions further dissociate into more hydronium ions and sulfate ions (SO42−). Concentrated sulfuric acid acts as a strong oxidizing and dehydrating agent, reacting vigorously with various substances.
Fuming Sulfuric Acid (Oleum): Refers to sulfur trioxide solutions in 100 percent sulfuric acid, often containing 20, 40, or 65 percent sulfur trioxide. These solutions, termed oleum, are crucial in the preparation of organic chemicals.

Understanding the sulfur cycle aids in comprehending how sulfur, in various forms, cycles through terrestrial and aquatic environments, impacting ecological processes and human activities alike.