Science, Tech, Math › Science Ideal Gas Law Definition and Equation Chemistry Glossary Definition of Ideal Gas Law Share Flipboard Email Print The ideal gas law relates temperature, pressure, volume, and amount of a gas. Brook Pifer / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 09, 2019 The ideal gas law is also known as the general gas equation. It is an equation of state of an ideal gas that relates pressure, volume, quantity of gas, and temperature. While the law describes the behavior of a hypothetical gas, it approximates the behavior of real gases in many situations. The law was first stated by Émile Clapeyron in 1834. The law combines Boyle's law, Avogadro's law, Gay-Lussac's law, and Charles' law. Equation The ideal gas law is the relationship described by the equation" PV = nRT where P is pressure, V is volume, n is the number of moles of an ideal gas, R is the ideal gas constant, and T is the temperature. Sources Clapeyron, E. (1834). "Mémoire sur la puissance motrice de la chaleur." Journal de l'École Polytechnique (in French). XIV: 153–90.Davis; Masten (2002). Principles of Environmental Engineering and Science. New York: McGraw-Hill. ISBN 0-07-235053-9.