Science, Tech, Math › Science Boiling Point Elevation Definition What Boiling Point Elevation Means in Chemistry Share Flipboard Email Print Salting water changes the boiling point of the liquid, producing boiling point elevation. Artur Debat / 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 May 07, 2019 Boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure are examples of colligative properties. These are properties of matter that are affected by the number of particles in a sample. Boiling Point Elevation Definition Boiling point elevation is the phenomenon that occurs when the boiling point of a liquid (a solvent) is increased when another compound is added, such that the solution has a higher boiling point than the pure solvent. Boiling point elevation occurs whenever a non-volatile solute is added to a pure solvent. While boiling point elevation depends on the number of dissolved particles in a solution, their identity is not a factor. Solvent-solute interactions also do not affect boiling point elevation. An instrument called an ebullioscope is used to accurately measure boiling point and thus detect whether boiling point elevation has occurred and how much the boiling point has changed. Boiling Point Elevation Examples The boiling point of salted water is higher than the boiling point of pure water. Salt is an electrolyte that dissociates into ions in solution, so it has a relatively large affect on boiling point. Note nonelectrolytes, such as sugar, also increase boiling point. However, because a nonelectrolyte does not dissociate to form multiple particles, it has less of an effect, per mass, than a soluble electrolyte. Boiling Point Elevation Equation The formula used to calculate boiling point elevation is a combination of the Clausius-Clapeyron equation and Raoult's law. It is assumed the solute is non-volatile. ΔTb = Kb · bB where ΔTb is the boiling point elevationKb is the ebullioscopic constant, which depends on the solventbB is the molality of the solution (typically found in a table) Thus, boiling point elevation is directly proportional to the molal concentration of a chemical solution.