https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:representing-chemical-reactions/v/intro-to-chemical-reactions-chemical-equation-and-reactions-chemistry-khan-academy 2026-04-08T23:10:43.121622596Z Intro to chemical equations Bonds between atoms or molecules are formed and/or broken during chemical reactions. Reactants are the inputs of a chemical reaction, and products are the outputs. Sal Khan video https://cdn.kastatic.org/googleusercontent/Z75oD-cJiGwdzgfe95kVhOnyPxF8KNuBGQi7d-Ap3DODJyIvHBOSqYwhAfUwvnRe4fqwLMRjq-YdEXlqakSM_ws Intro to chemical equations Bonds between atoms or molecules are formed and/or broken during chemical reactions. Reactants are the inputs of a chemical reaction, and products are the outputs. https://cdn.kastatic.org/ka-youtube-converted/1wQqGFebxyA.mp4/1wQqGFebxyA.mp4 344 Writing chemical equations https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:representing-chemical-reactions/e/apply-representing-chemical-reactions 2026-06-25T08:30:40.480891627Z Apply: Representing chemical reactions Apply your understanding of using chemical equations to represent chemical reactions in this set of free, standards-aligned practice questions. Fig exercise https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:representing-chemical-reactions/e/apply-counting-atoms-in-chemical-equations 2026-06-30T16:30:41.535282189Z Apply: Counting atoms in chemical equations Apply your understanding of subscripts and coefficients in chemical equations in this set of free, standards-aligned practice questions. Fig exercise https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:representing-chemical-reactions/a/symbols-in-chemical-equations 2026-04-28T11:00:37.315336883Z Learn and try: Symbols in chemical equations Learn the meaning behind the symbols we use to represent chemical reactions. article https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:types-of-chemical-reactions/v/combination-and-decomposition-reaction-chemical-reactions-and-equations-chemistry-khan-academy 2020-07-02T12:24:36Z Combination and decomposition reaction Reactions in which many reactants combine to give one product are called combination reactions whereas, in decomposition one reactant breaks down in many products Ram Prakash video https://cdn.kastatic.org/googleusercontent/R9gDwoK_GKlAUm5WmBQULqZXe5Ez_hq-Ebn_a5Xy6ouF49haYD9FIc0yMKDy6hdUunfMYOQi-coYiHBquK2mV78 Combination and decomposition reaction Reactions in which many reactants combine to give one product are called combination reactions whereas, in decomposition one reactant breaks down in many products https://cdn.kastatic.org/ka-youtube-converted/6esN2vQCwrY.mp4/6esN2vQCwrY.mp4 770 Writing chemical equations https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:types-of-chemical-reactions/e/apply-synthesis-and-decomposition 2026-05-04T07:50:51.861128514Z Apply: Synthesis, decomposition, and combustion reactions Apply your understanding of synthesis, decomposition, and combustion reactions in this set of free, standards-aligned practice questions. Allen Ruch exercise https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:types-of-chemical-reactions/v/single-replacement-reactions 2024-08-16T15:18:47.217883837Z Single replacement reactions When one element replaces another element in a compound, we call it a single replacement reaction. In these reactions, one atom loses electrons (oxidation) while another element gains those electrons (reduction), making them a form of a redox reaction. Learn to use the Activity Series, which ranks elements by their reactivity and helps predict if the reaction will occur. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/b0b1e8cf-9cb9-47d6-83a9-5468c15f9d1f_1280_720_base.png Single replacement reactions When one element replaces another element in a compound, we call it a single replacement reaction. In these reactions, one atom loses electrons (oxidation) while another element gains those electrons (reduction), making them a form of a redox reaction. Learn to use the Activity Series, which ranks elements by their reactivity and helps predict if the reaction will occur. https://cdn.kastatic.org/ka-youtube-converted/l1xCT77_UY4.mp4/l1xCT77_UY4.mp4 818 Writing chemical equations https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:types-of-chemical-reactions/e/apply-single-replacement-reactions 2026-04-29T10:50:35.589391704Z Apply: Single replacement reactions Apply your understanding of single replacement reactions in this set of free, standards-aligned practice questions. Allen Ruch exercise https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-reactions/x2613d8165d88df5e:types-of-chemical-reactions/a/single-replacement-reactions 2026-04-29T07:20:45.495372596Z Learn and try: Single replacement reactions Definition of single replacement (or single displacement) reactions. Predicting and determining the products using the reactivity series.  article https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:solutions-acids-and-bases/x2613d8165d88df5e:solubility/v/double-replacement-reactions 2024-08-16T15:18:47.217883837Z Double replacement reactions Double replacement reactions occur when two compounds exchange ions, forming two new compounds. The driving force in these reactions is often the formation of a precipitate, a gas, or water. A solubility chart is commonly used to predict whether a potential product will be insoluble and therefore precipitate out of solution. This allows us to determine if the reaction will actually occur. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/0918daf4-a77a-4427-a43c-53bae09bbd3f_1280_720_base.png Double replacement reactions Double replacement reactions occur when two compounds exchange ions, forming two new compounds. The driving force in these reactions is often the formation of a precipitate, a gas, or water. A solubility chart is commonly used to predict whether a potential product will be insoluble and therefore precipitate out of solution. This allows us to determine if the reaction will actually occur. https://cdn.kastatic.org/ka-youtube-converted/KDGDLsUN8TQ.mp4/KDGDLsUN8TQ.mp4 732 Writing chemical equations https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:solutions-acids-and-bases/x2613d8165d88df5e:solubility/e/apply-double-replacement-reactions 2026-04-29T07:20:45.495372596Z Apply: Double replacement reactions Check your understanding of double replacement and precipitation reactions in this set of free, standards-aligned practice questions. Allen Ruch exercise https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:solutions-acids-and-bases/x2613d8165d88df5e:solubility/a/double-replacement-reactions 2026-04-29T07:20:45.495372596Z Learn and try: Double replacement reactions Definition and examples of double replacement reactions. Predicting and balancing neutralization and precipitation reactions.  article https://www.khanacademy.org/science/bridge-course-class-11th-chemistry/x426c9d2c554669cb:types-of-chemical-reactions/x426c9d2c554669cb:different-types-of-chemical-reactions/v/all-types-of-reactions-solved-examples-chemical-reactions-chemistry-khan-academy 2020-07-02T12:24:37Z All types of reactions: Solved examples Let's solve some problems on identifying different types of chemical reactions. Ram Prakash video https://cdn.kastatic.org/googleusercontent/wTOAD1IGCL-HG_dL8mAFIqDTmg-2rgJwdJgbL09TdIRFlUGLHQRGxsHL9jlQFOy26pbERgR1nTwiApO3LVh8zjOdeg All types of reactions: Solved examples Let's solve some problems on identifying different types of chemical reactions. https://cdn.kastatic.org/ka-youtube-converted/kAKDFNWMixU.mp4/kAKDFNWMixU.mp4 483 Writing chemical equations https://www.khanacademy.org/science/telangana-class-10-physical-sciencein/x1ac9c643dc8dffee:chemical-reactions-and-equations/x1ac9c643dc8dffee:overview-on-chemical-reactions/e/completing-equations-and-identifying-types-of-reactions 2026-03-06T14:20:34.578397931Z Identifying types of reactions Let's practice on  identifying the type of reaction. Chaitra exercise https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:matter-and-energy-in-organisms/x0c5bb03129646fd6:food-and-energy-in-organisms/v/cellular-respiration-ms 2024-01-04T21:34:20.525650636Z Cellular respiration Cellular respiration is the process by which the body gets energy from food. It is a series of chemical reactions that happen in our cells, converting glucose from our food and oxygen from the air we breathe into carbon dioxide, water, and usable energy. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/2d58e357-a04c-4bdb-89a6-b7db087bb557_1280_720_base.png Cellular respiration Cellular respiration is the process by which the body gets energy from food. It is a series of chemical reactions that happen in our cells, converting glucose from our food and oxygen from the air we breathe into carbon dioxide, water, and usable energy. https://cdn.kastatic.org/ka-youtube-converted/1RXk1NJpRDI.mp4/1RXk1NJpRDI.mp4 227 Writing chemical equations https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:matter-and-energy-in-organisms/x0c5bb03129646fd6:food-and-energy-in-organisms/a/cellular-respiration 2026-04-26T16:30:39.382257956Z Key points: Cellular respiration Review your understanding of cellular respiration in this free article aligned to NGSS standards. article https://www.khanacademy.org/science/ap-biology/cellular-energetics/photosynthesis/a/intro-to-photosynthesis 2021-04-29T07:54:51Z Intro to photosynthesis Conversion of light energy to chemical energy. Reactions of photosynthesis, where they take place, and their ecological importance. article https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:global-change/x0b0e430a38ebd23f:climate-change/v/ocean-acidification 2024-06-28T21:00:15.59562973Z Ocean acidification Ocean acidification, a result of increased atmospheric carbon dioxide, is making our oceans more acidic, disrupting the formation of calcium carbonate in sea life and disturbing their homeostasis. This phenomenon is linked to emissions from human activities, such as the combustion of fossil fuels, driving vehicles, and deforestation. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/f325610b-22f7-4284-876a-a8bb55d7c250_1280_720_base.png Ocean acidification Ocean acidification, a result of increased atmospheric carbon dioxide, is making our oceans more acidic, disrupting the formation of calcium carbonate in sea life and disturbing their homeostasis. This phenomenon is linked to emissions from human activities, such as the combustion of fossil fuels, driving vehicles, and deforestation. https://cdn.kastatic.org/ka-youtube-converted/8JUEga3MYsM.mp4/8JUEga3MYsM.mp4 325 Writing chemical equations