Hydrofluoric acid

Hydrofluoric acid is a solution of hydrogen and fluoride in water. It is a precursor to almost all fluorine compounds, including the elemental fluorine itself. It is a colorless solution that is highly corrosive, capable of dissolving many materials, especially oxides. Its ability to dissolve glass has been known since the 17th century, even before Carl Wilhelm Scheele prepared it in large quantities in 1771. Because of its high reactivity toward glass and moderate reactivity toward many metals, hydrofluoric acid is usually stored in plastic containers. Hydrogen fluoride gas is an acute poison that may immediately and permanently damage lungs and the corneas of the eyes. Aqueous hydrofluoric acid is a contact-poison that can have deep, initially painless burns and ensuing tissue death. By interfering with body’s metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality, after contact with as little as 25 square inches of skin.

Properties
Its Physical state and appearance is a Liquid. It has a strong odor. It’s a colorless solution made up of water and hydrogen fluoride. It has a density of 1.15 g/ml. its Boiling Point is 108°C (226.4°F) and its Melting Point is -36.111°C (-33°F). Its acidity is 3.17 so it is a weak acid. It’s very hazardous and corrosive to human skin. It is easily soluble in cold water, hot water. Partially soluble in diethyl ether.

Synthesis
Hydrofluoric acid is usually made in a factory. It does not occur in nature. It is made from putting Dry Fluorspar (CaF2) and Sulphuric acid (H2SO4) and mixing them in a rotary kiln to create an endothermic reaction. The HF gas is then put in a washing column, then a condenser, then a distillation column. It is turned into Hydrofluoric acid.

Uses
Hydrofluoric acid has a variety of uses in industry and research. It is used as a starting material or intermediate in industrial chemistry, mining, refining, glass finishing, silicon chip manufacturing, and in cleaning. In metalworking, hydrofluoric acid is used as a pickling agent to remove oxides and other impurities from stainless and carbon steels because of its limited ability to dissolve steel. Because of its ability to dissolve most oxides and silicates, hydrofluoric acid is used for dissolving rock samples usually before the analysis. Also, this acid is used in acid maceration to extract organic fossils from the surrounding rocks. The rock with fossils may be immersed directly into the acid, which sticks to the organic component and allows the rock to be dissolved around it. Diluted hydrofluoric acid is used in the petroleum industry in a mixture with other acids, those acids could be HCl or organic acids, in order to stimulate the production of water, oil, and gas wells specifically where sandstone is involved. Hydrofluoric acid is also used by some collectors of antique glass bottles to remove the remaining contents from the glass, caused by acids, usually in the soil the bottle was buried in, attacking the soda content of the glass. Other printing companies use hydrofluoric acid to remove unwanted images from printing plates. Felt-tip markers are available to make the process safer for the worker.



Health/Safety
Hydrofluoric Acid is one of the most dangerous acids known. It needs to be treated differently than even strong acids like Sulfuric and Hydrochloric. The Hydrogen Fluoride molecule is so mobile that it may easily pass through the skin. Because Fluorine has an extremely high affinity for Calcium, bones will be attacked, and this may result in hypocalcaemia. There may be no pain immediately after the burn, leading the injured person to believe that they are not in danger. It is so potent that contact with it may not even be noticed until long after serious damage has been done. Even very strong acids, and mixtures of acids do not have the power to cause death and injury in the way that Hydrofluoric Acid can.

Wear personal protective equipment when handling any amount of HF including gloves, goggles, face shield, and a lab coat. HF should always be used in a chemical fume hood.

The contact of concentrated solutions of HF (from 49%) with skin immediately causes severe and painful lesions. Then the damaged area of skin discolors and becomes whitish or grayish at the center, surrounded by a purplish crown. If the time of contact increases, the damaged skin turns to red then to grayish purple/black purple, with an intense pain.

Video
In this Video the Mythbusters attempt to see if Hydrofluoric acid can be used to melt a body like it dones in the show Breaking Bad. u6EGbz2SJmI