Sulphuric acid, which has the chemical formula H2SO4, is an acidic substance. It is known as the king of chemicals because it is frequently utilized in various industries. Its production across the globe shows its industrial strength. Its global production peaked in 2004 at 180 million tonnes and the oil of vitriol is another name for it. It is a viscous liquid that is colourless, odourless, and soluble in water. Sulphuric acid is often prepared by a highly exothermic reaction involving heat release.
Did You Know? A highly contracted sulphuric acid may catch fire if it is diluted using water due to its exothermic reaction.
What is Sulphuric Acid?
Sulphuric acid, also known as oil of vitriol in antiquity, is a mineral acid made up of elements like hydrogen, oxygen, and sulphur. It has the chemical formula H2SO4. It is a viscous liquid that is not soluble in water. It has no colour or smell. Due to its strong affinity for water vapour, pure sulphuric acid does not naturally occur on Earth. It is hygroscopic and rapidly collects water vapour from the air.
Since concentrated sulphuric acid is a strong oxidant with strong dehydrating effects, it is extremely corrosive to other materials, including rocks and metals. A major exception is that sulphuric acid does not dehydrate phosphorus pentoxide. On the contrary, phosphorus pentoxide dehydrates sulphuric acid into sulphur trioxide.
Since a significant amount of heat is created when sulphuric acid is added to water, it is not advisable to do the process in reverse. This is because it could cause the solution to boil and release hot acid droplets. Sulphuric acid can result in severe acidic chemical burns and even secondary thermal burns from dehydration when it comes into contact with bodily tissue. Diluted sulphuric acid still needs to be handled carefully due to its acidity, even though it is significantly less dangerous due to the absence of oxidative and dehydrating effects.
Preparation of Sulphuric Acid by Contact Process
Sulphuric acid can generally be prepared in several ways with different labor, expense, and purity levels. The contact process is one of the most frequently used processes among all of these.
Sulphuric acid is produced using the contact method consisting of four steps:
Extraction of Sulphur
For the production of sulphur dioxide gas, pure sulphur is needed. Sulphur can be collected from several different sources, but recovery from natural gas and oil is the most significant. The organic or mineral components are removed from them to obtain sulphur.
Sulphur dioxide can be extracted in addition to pure sulphur in several ways. Refining metal is one of them. Many metal ores are found in soil, like sulfides, which are then burned to produce the corresponding oxide and sulphur dioxide.
Conversion of Sulphur Dioxide to Sulphur Trioxide
At this stage, the contact method is quite simple. This process is only partially complete because it generates corrosive sulphur trioxide that can be reversed and involves several reaction conditions to create the intended product. Sulphur dioxide and oxygen are mixed in a lead chamber in a 1:1 ratio. The temperature is set at 400 to 450 degrees Celsius. The vanadium pentoxide catalyst catalyzes the procedure.
Conversion of Sulphur Trioxide to Sulphuric Acid
Sulphur trioxide can be diluted in water to produce sulphuric acid. This procedure is not used frequently at room temperature since it is an extremely exothermic reaction involving releasing a huge amount of heat, making it risky. As a result, the gases stop sulphur trioxide from further dissolving in water.
Application of Sulphuric Acid
Sulphuric acid is used in many forms and types in different products and equipment. Following is a summary of its usage:
- Sulphuric acid is used to produce fertilizers. The chemical content of fertilizers is phosphate and nitrate, extracted from sulphuric acid.
- Sulphuric acid is also used to produce aluminium sulfate, also known as makers’ alum, used in water treatment plants to purify the water.
- Due to its strong dehydration properties, it is also used to purify metals such as aluminium or steel from rust.
- Hydrogen peroxide can be added to sulphuric acid to form piranha solution, a highly toxic and acidic cleaning solution used to clean glass tubes and jars in laboratories.
- Sulphuric acid is also a reactive agent for various other reactions, like refining petroleum to extract petroleum from crude oil.
- Acids are good conductors of electricity. But, hardly any other acid functions like an electrolyte than sulphuric acid.
- The main component of acidic drain cleaners, which are used to remove oil, hair, tissue paper, etc., is typically sulphuric acid in high concentration. Additionally, as concentrated sulphuric acid has a high dehydrating effect, it can also remove tissue paper through the dehydrating process.
Sulphuric acid is one of the most commonly used chemicals in industries and homes. It is used in zinc lead batteries to hold the charge and to produce fertilizers and other essentials of human life. There are multiple ways to produce sulphuric acid. The most common is the contract process. As part of the process, sulphur is extracted through multiple chemical reactions or metal ores. The extracted sulphur is then heated in oxygen to extract sulphur trioxide. Finally, the sulphur trioxide is diluted in water, and the hydrogen molecules react with sulphur to produce sulphur dioxide or trioxide.
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