Science, Tech, Math › Science Partial Pressure Definition and Examples What Does Partial Pressure Mean? Share Flipboard Email Print Each gas in a mixture of gases contributes a partial pressure. The sum of all the partial pressures it the total pressure of the mixture. Víctor Del Pino / EyeEm / 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 February 12, 2019 Partial Pressure Definition In a mixture of gases, each gas contributes to the total pressure of the mixture. This contribution is the partial pressure. The partial pressure is the pressure the gas if the gas were in the same volume and temperature by itself. Dalton's law states the total pressure of a mixture of ideal gases is the sum of the partial pressure of each individual gas. While the usual symbol for pressure is P or p, partial pressure is indicated by a subscript (e.g., P1 or p1). Partial pressure is important in the fields of chemistry, physics, and biology. Blood levels of oxygen and carbon dioxide are determined by measuring their partial pressure. Source Perry, R.H. and Green, D.W. (Editors) (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill. ISBN 0-07-049841-5.