Hydrochloric acid

Properties

General
Name	Hydrogen chloride
Chemical formula	HCl
Appearance	Colourless gas
Physical
Formula weight	36.5 amu
Melting point	159 K (-114 °C)
Boiling point	188 K (-85 °C)
Density	1.2 ×103 kg/m3 (liquid)
Solubility	70 g in 100g water
Thermochemistry
ΔfH0gas	-92.31 kJ/mol
ΔfH0liquid	? kJ/mol
ΔfH0solid	? kJ/mol
S0gas, 1 bar	186.9 J/mol·K
S0liquid, 1 bar	? J/mol·K
S0solid	? J/mol·K
Safety
Ingestion	Toxic, can be fatal.
Inhalation	Fumes may be fatal. Do not give unprotected mouth-to-mouth resuscitation.
Skin	May cause severe burns.
Eyes	Extremely dangerous.
More info	Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals/2/1160.html)
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references

The chemical compound hydrochloric acid is a highly acidic aqueous solution of hydrogen chloride (HCl). It is highly corrosive and should only be handled with appropriate precautions. Hydrochloric acid is a commonly used chemical reagent and is one of the strong acids that ionize completely in aqueous solution. Concentrated hydrochloric acid has a pH of less than 1.

An old (pre-systematic) name for hydrochloric acid is muriatic acid, from before the discovery of the element chlorine and the establishment of the acid's formula as HCl. It is still sold by industrial suppliers and hardware stores under the old name for removing mortar stains and film from brick, masonry, and stone work. The adjective muriatic means "pertaining to brine or salt", presumably from the chlorine component.

Hydrochloric acid was known to alchemists as 'spirit of salt' or acidum salis. Gaseous HCl was called 'marine acid air'.

Aqua regia is an old name for a mixture of hydrochloric and nitric acids.

Human digestive fluids consist of a mixture of hydrochloric acid and various enzymes which help break down stomach contents.

Hydrochloric acid is manufactured by burning chlorine gas in hydrogen to make hydrogen chloride gas, and then dissolving the gas in water.

Hydrochloric acid is generally purchased in a concentrated form and is diluted in a fume cupboard see making up solutions.

External Links

• EPA Hazard Summary (http://www.epa.gov/ttn/uatw/hlthef/hydrochl.html)
• NIH Description and Hazard Summary (http://www.cc.nih.gov/cp/about_lab_med/hcl.html)