https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/v/chemical-changes 2025-03-21T20:29:57.678923887Z Chemical changes A chemical change occurs when a substance transforms into one or more new substances with different properties. Chemical reactions often involve color changes, gas production, odor changes, precipitate formation, or energy changes like heat or light. Unlike physical changes, chemical changes alter a substance’s identity, making them key to understanding chemical properties. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/3665da2c-e708-41b0-a732-779264ca6d87_1280_720_base.png Chemical changes A chemical change occurs when a substance transforms into one or more new substances with different properties. Chemical reactions often involve color changes, gas production, odor changes, precipitate formation, or energy changes like heat or light. Unlike physical changes, chemical changes alter a substance’s identity, making them key to understanding chemical properties. https://cdn.kastatic.org/ka-youtube-converted/CT5CVpOVAoY.mp4/CT5CVpOVAoY.mp4 445 Chemical changes https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/a/chemical-properties-and-changes 2026-04-15T09:00:48.368849752Z Learn and try: Chemical properties and changes Learn how to identify chemical properties of substances and distinguish chemical changes from physical changes. Explore the signs that indicate a chemical reaction has occurred and how new substances with different properties are formed. article https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/e/understand-chemical-changes 2026-06-29T17:40:41.821508738Z Understand: Chemical changes Check your understanding of chemical changes and chemical reactions in this set of free, standards-aligned practice questions. donna exercise https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/e/apply-chemical-changes 2026-06-29T17:40:41.821508738Z Apply: Chemical changes Apply your understanding of chemical changes and chemical reactions in this set of free, standards-aligned practice questions. donna fig exercise