Science, Tech, Math › Science Binary Acid Definition in Chemistry What Is a Binary Acid? Share Flipboard Email Print Hydrochloric acid is an example of a binary acid. ollaweila, 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 July 08, 2019 A binary acid is a binary compound where one element is hydrogen and the other is a nonmetal. Binary acids are also known as hydracids. Binary Acid Examples Hydrochloric acid (HCl), hydrofluoric acid (HF), and hydroiodic acid (HI) are all binary acids. Hydrogen sulfide (H2S) is a binary acid. Even though a hydrogen sulfide molecule consists of three atoms, there are only two elements. One is hydrogen, while sulfur is a nonmetal.