BOILING DEFINITION IN CHEMISTRY - Boiling and evaporation do not mean the same thing. Boiling occurs throughout the volume of a liquid, while evaporation only occurs at the surface interface between the liquid and its surroundings. The bubbles that form during boiling do not form during evaporation. In evaporation, the liquid molecules have different kinetic energy values from one another.

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Boiling Definition in Chemistry

Chemistry Glossary Definition of Boiling

by Anne Marie Helmenstine, Ph.D. 

Boiling is defined as a phase transition from the liquid state to the gas state, usually occurring when a liquid is heated to its boiling point.

At the boiling point, the vapor pressure of the liquid is the same as the external pressure acting upon its surface.

Also Known As: Two other words for boiling are ebullition and vaporization.

Boiling Example

A good example of boiling is seen when water is heated until it forms steam.

The boiling point of fresh water at sea level is 212°F (100°C). 

The bubbles that form in the water contain the vapor phase of water, which is steam. The bubbles expand as they get closer to the surface because there is less pressure acting upon them.

Boiling Versus Evaporation

In the process of evaporation, particles may transition from the liquid phase to the gas phase.

However, boiling and evaporation do not mean the same thing.

Boiling occurs throughout the volume of a liquid, while evaporation only occurs at the surface interface between the liquid and its surroundings.

The bubbles that form during boiling do not form during evaporation. In evaporation, the liquid molecules have different kinetic energy values from one another.

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.

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https://www.thoughtco.com/definition-of-boiling-604389