VOLATILE SUBSTANCES - Volatility is a measure of how readily a substance vaporizes or transitions from a liquid phase to a gas phase. The term can also be applied to the phase change from solid state to vapor, which is called sublimation. A volatile substance has a high vapor pressure at a given temperature compared with a nonvolatile compound. The higher the vapor pressure of a compound, the more volatile it is. Higher vapor pressure and volatility translate into a lower boiling point.

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Volatile Substances

What Is a Volatile Substance in Chemistry?

Volatility refers to a substance's ability to vaporize

by Anne Marie Helmenstine, Ph.D.

In chemistry, the word "volatile" refers to a substance that vaporizes readily.

Volatility is a measure of how readily a substance vaporizes or transitions from a liquid phase to a gas phase.

The term can also be applied to the phase change from solid state to vapor, which is called sublimation.

A volatile substance has a high vapor pressure at a given temperature compared with a nonvolatile compound.

Examples of Volatile Substances

·       Mercury is a volatile element. Liquid mercury had a high vapor pressure, readily releasing particles into the air.

·       Dry ice is a volatile inorganic compound that sublimates at room temperature from the solid phase into carbon dioxide vapor.

·       Osmium tetroxide (OsO₄) is another volatile inorganic compound that, like dry ice, transitions from the solid phase to the vapor phase without becoming a liquid.

·       Many organic compounds are volatile. An example is alcohol. Because volatile substances readily vaporize, they mix with air and may be smelled (if they have an odor).

Xylene and benzene are two volatile organic compounds with distinctive scents.

Relationship Between Volatility, Temperature, and Pressure

The higher the vapor pressure of a compound, the more volatile it is. Higher vapor pressure and volatility translate into a lower boiling point.

Increasing temperature increases vapor pressure, which is the pressure at which the gas phase is in equilibrium with the liquid or solid phase. 

Anne Marie Helmenstine, Ph.D.

·   Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.

·   Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.

·   ThoughtCo and About Education chemistry expert since 2001.

·   Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.

Experience

Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.

In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor.

Education

Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.

Anne Marie Helmenstine, Ph.D.​

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https://www.thoughtco.com/definition-of-volatile-604685