Science, Tech, Math › Science Chemical Reaction vs. Chemical Equation Do you know the difference? Share Flipboard Email Print Jeffrey Coolidge / Getty Images Science Chemistry Basics Chemical Laws 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 September 22, 2019 What is the difference between a chemical reaction and the chemical equation? These terms are often used interchangeably, but although they're related, they're different things. A chemical reaction is a process that occurs when one or more substances are changed into one or more new substances. For example: Hydrogen and oxygen gas combine to produce water.Sodium chloride (table salt) dissociates in water to form sodium and chlorine ions.Methane combusts in oxygen to form carbon dioxide, heat, and water. On the other hand, a chemical equation is the symbolic representation of a chemical reaction. Atomic symbols are used to represent the elements that take part in a reaction. The numbers represent the ratios of reactants and products that produce the reaction. Arrows point the direction a reaction occurs, with the arrow pointing from reactants to products. For example, using for the above chemical reactions: 2 H2(g) + O2(g) → 2 H2O(ℓ)This chemical equation reads: Two hydrogen gas molecules and one oxygen gas molecule produce two molecules of water.NaCl(s) + H2O → Na+(aq) + Cl-(aq)One molecule of sodium chloride dissociates in water into one sodium ion and one chlorine ion.CH4 + 2 O2 → CO2 + 2 H2O (&DeltaH = -891 kJ/mol)This equation shows one methane molecule and two oxygen gas molecules form a carbon dioxide molecule, two water molecules and release 891 kilojoules of heat. To review:Chemical reactions are processes in which reactants become new products.Chemical equations are the symbolic representation of chemical reactions.