Science, Tech, Math › Science Normality Definition in Chemistry Share Flipboard Email Print Steve McAlister/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 January 31, 2020 Normality is a measure of concentration equal to the gram equivalent weight per liter of solution. Gram equivalent weight is the measure of the reactive capacity of a molecule. The solute's role in the reaction determines the solution's normality. Normality is also known as the equivalent concentration of a solution. Normality Equation Normality (N) is the molar concentration ci divided by an equivalence factor feq: N = ci / feq Another common equation is normality (N) is equal to the gram equivalent weight divided by liters of solution: N = gram equivalent weight/liters of solution (often expressed in g/L) Or it might be the molarity multiplied by the number of equivalents: N = molarity x equivalents Units of Normality The capital letter N is used to indicate concentration in terms of normality. It can also be expressed as eq/L (equivalent per liter) or meq/L (milliequivalent per liter of 0.001 N, typically reserved for medical reporting). Examples of Normality For acid reactions, a 1 M H2SO4 solution will have a normality (N) of 2 N because 2 moles of H+ ions are present per liter of solution.For sulfide precipitation reactions, where the SO4- ion is the important part, the same 1 M H2SO4 solution will have a normality of 1 N. Example Problem Find the normality of 0.1 M H2SO4 (sulfuric acid) for the reaction: H2SO4 + 2 NaOH → Na2SO4 + 2 H2O According to the equation, 2 moles of H+ ions (2 equivalents) from sulfuric acid react with sodium hydroxide (NaOH) to form sodium sulfate (Na2SO4) and water. Using the equation: N = molarity x equivalentsN = 0.1 x 2N = 0.2 N Don't be confused by the number of moles of sodium hydroxide and water in the equation. Since you've been given the molarity of the acid, you don't need the additional information. All you need to figure out is how many moles of hydrogen ions are participating in the reaction. Since sulfuric acid is a strong acid, you know it completely dissociates into its ions. Potential Issues Using N for Concentration Although normality is a useful unit of concentration, it can't be used for all situations because its value depends on an equivalence factor that can change based on the type of chemical reaction of interest. As an example, a solution of magnesium chloride (MgCl2) might be 1 N for the Mg2+ ion, yet 2 N for the Cl- ion. While N is a good unit to know, it's not used as much as molality in actual lab work. It has value for acid-base titrations, precipitation reactions, and redox reactions. In acid-base reactions and precipitation reactions, 1/feq is an integer value. In redox reactions, 1/feq might be a fraction.