Shown here are four ways that chemists represent a molecule of nitric acid. In the colored models, nitrogen is blue, oxygen is red, and hydrogen is white.
Click on image for full size
Windows to the Universe original artwork by Randy Russell.

Nitric Acid - HNO3

Nitric acid is a colorless, corrosive liquid and a toxic acid which can cause severe burns. Nitric acid consists of nitrogen, oxygen, and hydrogen atoms. Nitric acid, in its gas phase, is present in very small quantities in Earth's atmosphere.

Nitric acid is one of the components of acid rain. Clean air has very little nitric acid in it, but some types of pollution generate this acid. For example, the engines of motor vehicles produce nitrogen oxide compounds when they burn their fuel. Nitrogen dioxide (NO2) from car exhaust turns into nitric acid when it mixes with water vapor. This mixture falls from the sky as acid rain.

The Persian alchemist Jabir ibn Hayyan first synthesized nitric acid around 800 A.D. Nitric acid is used in the manufacture of explosives, including nitroglycerin and trinitrotoluene (TNT). Nitric acid is also involved in the production of chemical fertilizers such as ammonium nitrate. Because it is such a strong acid, nitric acid is also widely used in industry for cleaning and etching metal, electroplating, refining, photoengraving, and in jewelry manufacturing. It is also used as an oxidizer in some liquid-fueled rockets.

Humans generate nitric acid wherever very high temperature combustion takes place in the atmosphere in the presence of nitrogen, oxygen and water. The exhausts of incinerators or other chemical plants and the tailpipes of cars and trucks are common sources. Because it is so reactive with other compounds, nitric acid does not remain in Earth's atmosphere for long. Nitric acid reacts with gaseous ammonia to form particulate or aerosol nitrate, removing the nitric acid from the atmosphere within a few days of its creation.

Last modified February 2, 2006 by Randy Russell.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Nitrogen

Nitrogen is a chemical element with an atomic number of 7 (it has seven protons in its nucleus). Molecular nitrogen (N2) is a very common chemical compound in which two nitrogen atoms are tightly bound...more

Oxygen

Oxygen is a chemical element with an atomic number of 8 (it has eight protons in its nucleus). Oxygen forms a chemical compound (O2) of two atoms which is a colorless gas at normal temperatures and pressures....more

Acid Rain

Acid rain is a general term used to describe different kinds of acidic air pollution. Although some acidic air pollutants return directly back to Earth, a lot of it returns in rain, snow, sleet, hail,...more

Air Pollution

What do smog, acid rain, carbon monoxide, fossil fuel exhausts, and tropospheric ozone have in common? They are all examples of air pollution. Air pollution is not new. As far back as the 13 th century,...more

Air Pollution and Water

Many people are aware of the fact that water can be contaminated from trash, oil spills, sewage, fertilizers, and chemicals from factories. Few realize that water can also be contaminated from air pollution...more

Air Pollution Sources

Air pollution comes from many different sources. Natural processes that affect air quality include volcanic activity, which produce sulfur, chlorine, and ash particulates, and wildfires, which produce...more

Ammonia - NH3

Ammonia is a chemical compound that is a colorless, flammable gas at normal temperatures and pressures. Ammonia is toxic, corrosive to some materials, and has a pungent odor. An ammonia molecule (NH3)...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA