Sulfuric acid

Structure of the sulfuric acid molecule, showing atoms as colored orbs. The yellow orb in the middle is sulfur, the red orbs surrounding it are oxygen, and the white orbs on two of the oxygins are hydrogen.

Concentrated sulfuric acid burning tissue paper

Sulfuric acid, also known as sulphuric acid, is a chemical compound and strong acid. Its chemical formula is H₂SO₄.

Salts of sulfuric acid are called sulfates.

History

Sulfuric acid is one of the oldest known mineral acids.

Alchemists called it "oil of vitriol", because they made it from sulfate salts that they called vitriols (from the Latin word for "small glass", as the salts looked like glass). The preparation of sulfuric acid from vitriol is traditionally credited to Jabir ibn Hayyan, known in Europe as Geber, but historians believe they were the work of another author, Pseudo-Geber, who said ibn Hayyan wrote their work so it would be taken more seriously. The oldest verifiable recipes for sulfuric acid date to the 16th century.

The contact process used to make industrial strength sulfuric acid was invented in the 19th century, and continues to be used today.

Properties

It is a dense (thick), clear, corrosive liquid that can dissolve in water. It can also melt through some weak substances.

History

It was once known as "oil of vitriol". This name was created by Jabir ibn Hayyan, the person who discovered it. It used to be prepared by the reaction of potassium nitrate with sulfur. This reaction would produce sulfur trioxide which would dissolve in steam to produce sulfuric acid. Then this reaction was done in lead containers. The contact process, the most common process, was invented in 1831 and is still used today.

Production

It is made by reacting sulfur trioxide with sulfuric acid to produce oleum. Then oleum is dissolved in water to produce more sulfuric acid. The sulfur trioxide is produced by burning sulfur to produce sulfur dioxide, which was then oxidized to sulfur trioxide with a catalyst. This process is called the contact process.

Uses

Sulfuric acid has many uses. World production in 2001 was 165 million tons, worth about $8 billion US dollars. Uses include ore processing, fertilizer manufacturing, oil refining, wastewater processing, lead acid batteries, and combining chemicals for scientific reasons. For example, phosphate rocks are reacted with sulfuric acid to produce soluble phosphates, useful in fertilizers. This reaction is also used to make phosphoric acid, useful in soda. Potassium compounds are dissolved in sulfuric acid to produce potassium sulfate, useful in fertilizers. Ammonia is also reacted with sulfuric acid to produce ammonium sulfate. These three chemicals are solids and provide the three main minerals needed in plants. Lead acid batteries use sulfuric acid as their electrolyte.

Reactions and safety

Sulfuric acid is very poisonous because of its acidity and corrosiveness. When it is mixed with sugar, it turns it into carbon. When it is dissolved in water, it becomes less harmful but is still corrosive like normal acids. It reacts with metals to produce hydrogen and the metal sulfate. Some metals, such as tin, make sulfur dioxide and tin(II) sulfate. It reacts with sodium chloride to make hydrogen chloride.

Related pages

• Sulfurous acid
• Hydrogen sulfide